Why were Paul's companions said to be standing up and seeing but not hearing in Acts9 and then all falling down and not hearing in Acts 22 and Acts 26?
1 But still breathing threats and murder toward the
disciples of the Lord, coming to the high priest,
2 Saul asked from him letters to Damascus, to the synagogues, so that if he found any being of the Way, both men and women, having bound them he might bring [them] to Jerusalem.
3 But in the going it happened! He drew near to Damascus, and suddenly a light from the heaven shone around him.
4 And falling on the earth he heard a voice saying to him, Saul, Saul! Why do you persecute Me?
5 And he said, Sir, who are You? And the Lord said, I am Jesus, whom you persecute; [it is] hard for you to kick against the goads.
6 Both trembling and being astonished he said, Lord, what do You desire me to do? And the Lord said to him, Rise up and go into the city, and it will be told you what you must do.
7 But the men travelling with him had been standing speechless [pluperfect tense. You cannot fall unless you have been standing in the first place], indeed hearing of the voice [Genitive not accusative. This is not hearing the voice, it is hearing of the voice], but seeing no one. [does not say they did not see the light. They did not see the speaker Jesus]
8 And Saul was lifted up from the earth, but his eyes being opened he saw no one. And leading him by the hand they brought [him] to Damascus.
9 And he was three days not seeing, and did not eat or drink. (Acts 9 GLT)
4 [I] persecuted this Way as far as death, binding and
delivering up both men and women to prisons,
5 as also the high priest and all the elderhood witnesses to me. And receiving letters from [them] to the brothers, I travelled into Damascus even to lead those to Jerusalem being bound there, in order that they might be punished.
6 And it happened to me, travelling and drawing near to Damascus: suddenly, about midday, a great light out of the heaven shone around me.
7 And I fell to the ground, and heard a voice saying to me, Saul, Saul, why do you persecute Me?
8 And I answered, Who are you, Sir? And He said to me, I am Jesus the Nazarene whom you persecute.
9 But those being with me indeed saw the light, and were alarmed, but did not hear his voice [accusative. They hear is audibly but they do not understand it] speaking to me.
10 And I said, What shall I do, Lord? And the Lord said to me, Rising up, go into Damascus, and there you will be told about all things which are appointed to you to do.
11 And as I did not see, from the glory of that light, being led by the hand by those being with me, I went into Damascus.
12 And a certain Ananias, a devout man according to the Law, having been testified to by all the Jews living [there], (Acts 22 GLT)
10 which I also did in Jerusalem, I also shut up many
of the saints in prisons, receiving authority from the chief priests; and they
being put to death, I cast a vote.
11 And often punishing them through all the synagogues, I compelled [them] to blaspheme. And [being] exceedingly furious against them, I even persecuted as far as the outside cities.
12 In which also travelling to Damascus with authority and decision power from the chief priests,
13 at midday along the highway, [O] king, I and those with me saw a light from heaven shining around me above the brightness of the sun.
14 And all of us falling to the ground [after having been standing], I heard a voice speaking to me, and saying in the Hebrew dialect, Saul, Saul why do you persecute Me? [the others with him may not have understood that dialect] [It is] hard for you to kick against the prods.
15 And I said, Who are you, Sir? And He said, I am Jesus whom you persecute;
16 but rise up and stand on your feet, for [it is] for this reason I appeared to you, to appoint you a servant and a witness both of what you saw, and in what I shall appear to you,
17 having delivered you from the people and the nations, to whom I now send you,
18 to open their eyes, and to turn [them] from darkness to light, and [from] the authority of Satan to God, in order that they [may] receive remission of sins, and an inheritance among those being sanctified by faith in Me.
19 Upon this, king Agrippa, I was not disobedient to the heavenly vision, (Acts 26 GLT)
 The Law of the Light and the Law of the Darkness
7 forming [rc,yE] light, and creating [ar"B'] darkness; making [hf' peace, and creating [ar"B] evil. I, Jehovah, do [hf'['] all these things. (Isaiah 45 GLT)
rc,yE to form or formulate ar"B' to carve out or separate from hf'[' to labour/work/make
So a more precise translation would be...
7 Forming [rc,yE] light, and carving [ar"B'] out darkness, making [hf' peace, and carving out [ar"B] evil, I, [am] Jehovah, doing/making [hf'['] all these things.' (Isaiah 45)
Jehovah is carving out evil in the sense of defining it as lawlessness which is symbolised by darkness. He is making a separation between the light and the darkness, the lawful and the lawless. He forms or formulates light, which shows you which way to go and is the law of what you should do. Then he carves out darkness, which is the law of what you should not do.
4 The Rock, perfect is his activity, For all his ways are justice. A God of faithfulness, with whom there is no injustice; Righteous and upright is he. (Deuteronomy 32 NWT)
So God cannot do evil, he cannot himself sin, breaking a law which he has signed up to. But he can and does define evil, being a lawmaker.
5 And this is the message which we have heard from Him, and we proclaim to you: God is light, and no darkness is in Him, none! (1 John 1 GLT)
9 out of the 10 commandments were all prohibitions, these were the law of the darkness. Then Jesus elevated two other laws to be commandments or exhortations, which are the law of the light.
36 Teacher, which is the greatest commandment in the
37 He said to him: You must love Jehovah your God with your whole heart and with your whole soul and with your whole mind.
38 This is the greatest and first commandment.
39 The second, like it, is this: You must love your neighbour as yourself.
40 On these two commandments the whole Law hangs, and the Prophets (Matthew 22).
These are both proactive exhortations. Whereas the 10 commandments say...
And God proceeded to speak all these words, saying:
2 I am Jehovah your God, who have brought you out of the land of Egypt, out of the house of slaves. 
3 You must not have any other gods against my face. 
4 You must not make for yourself a carved image or a form like anything that is in the heavens above or that is on the earth underneath or that is in the waters under the earth. 
5 You must not bow down to them nor be induced to serve them, because I Jehovah your God am a God exacting exclusive devotion, bringing punishment for the error of fathers upon sons, upon the 3rd generation and upon the 4th generation, in the case of those who hate me.
6 But exercising loving-kindness toward the thousandth generation in the case of those who love me and keep my commandments .
7 You must not take up the name of Jehovah your God in a worthless way, for Jehovah will not leave the one unpunished who takes up his name in a worthless way .
8 Remembering the sabbath day to hold it sacred, 
9 you are to render service and you must do all your work 6 days. 
10 But the 7th day is a sabbath to Jehovah your God. You must not do any work, you nor your son nor your daughter, your slave man nor your slave girl nor your domestic animal nor your alien resident who is inside your gates. 
11 For in 6 days Jehovah made the heavens and the earth, the sea and everything that is in them, and he proceeded to rest on the 7th day. That is why Jehovah blessed the sabbath day and proceeded to make it sacred. 
12 Honor your father and your mother in order that your days may prove long upon the ground that Jehovah your God is giving you. 
13 You must not murder. 
14 You must not commit adultery. 
15 You must not steal. 
16 You must not testify falsely as a witness against your fellowman. 
17 You must not desire your fellowman's house. You must not desire your fellowman's wife, nor his slave man nor his slave girl nor his bull nor his ass nor anything that belongs to your fellowman  (Exodus 20).
Only the 5th commandment to honour your parents carries a promise with it. This is because it is an exhortation to walk in the light rather than a prohibition from walking in the darkness.
So crudely speaking. Jesus told us what we should do and Moses told us what we shouldn't do.
Those who walk in the light find peace. Those who walk in the darkness do evil. For peace and evil and the consequences of light and dark behaviour.
19 Now this is the basis for judgment, that the light
has come into the world but men have loved the darkness rather than the light,
for their works were wicked.
20 For he that practices vile things hates the light and does not come to the light, in order that his works may not be reproved.
21 But he that does what is true comes to the light, in order that his works may be made manifest as having been worked in harmony with God. (John 3 NWT)
The noun peace ~Alv' is from the root ~l;v an adjective meaning. whole, entire (Gesenius)