See footnote at the end of this answer, which I added on July 3, 2020
If Jesus' comment about being "lifted up" were an obfuscation (and I'm not saying it was), it wouldn't be the first time!
For some of Jesus' audiences, his use of obfuscation was deliberate. In his modus operandi, obfuscation was one way for him to separate the sheep from the goats, so to speak; i.e., the believers from the unbelievers, hangers-on, and lookyloos. Jesus' classic statement in this regard was
"'I speak to them in parables; because while seeing they do not see, and while hearing they do not hear, nor do they understand. In their case the prophecy of Isaiah is being fulfilled, which says, YOU WILL KEEP ON HEARING, BUT WILL NOT UNDERSTAND; YOU WILL KEEP ON SEEING, BUT WILL NOT PERCEIVE; FOR THE HEART OF THIS PEOPLE HAS BECOME DULL, WITH THEIR EARS THEY SCARCELY HEAR, AND THEY HAVE CLOSED THEIR EYES, OTHERWISE THEY WOULD SEE WITH THEIR EYES, HEAR WITH THEIR EARS, AND UNDERSTAND WITH THEIR HEART AND RETURN, AND I WOULD HEAL THEM. But blessed are your eyes, because they see; and your ears, because they hear. "For truly I say to you that many prophets and righteous men desired to see what you see, and did not see it, and to hear what you hear, and did not hear it'" (Matthew 13:13-17).
Jesus was not necessarily saying here that his disciples understood everything he taught them. In fact, John tells us in his gospel that when Christ made his "Triumphal Entry" into Jerusalem in fulfillment of Zechariah's prophecy about the king who would sit on a donkey, the disciples were in the dark:
"These things his disciples did not understand at the first; but when Jesus was glorified, then they remembered that these things were written of Him, and that they had done these things to Him" (12:16 NAS).
Getting back to the passage at hand, I put forward a couple questions of my own:
To whom was Jesus speaking in 12:32?
Was he still addressing the Greeks who approached Philip hoping he would take them to Jesus? It's quite possible Jesus didn't speak to the Greeks at all, and that his remarks were addressed only to Philip and Andrew (i.e., the "them" of v.23 in the NASB).
While the good news of the Kingdom of God was addressed primarily to "the lost sheep of the house of Israel" (Matthew 10:6; 15:24), I cannot see Jesus refusing to grant an audience to these God-fearing Greeks (as Luke might have called them). Nevertheless, Jesus' initial remark about the hour of the glorification of the Son of Man could very well have been Jesus' way of saying to Andrew and Philip,
"Friends, at this point in my ministry I'm thinking about one thing, and one thing only; namely, my soon-approaching glorification through death."
Put differently, Jesus may have been telling Philip and Andrew that he had more important things to do than to satisfy the curiosity of some Greeks, even God-fearing Greeks.
When we come to the next section of the story starting in verse 27, we hear Jesus saying,
"'Now my soul has become troubled; and what shall I say, 'Father, save Me from this hour?' But for this purpose I came to this hour. 'Father, glorify Your name'" (vv.27-28a NASB).
After the Father granted Jesus' request to glorify the Father's name and spoke to Jesus audibly from heaven, John tells us in verse 29,
"So the crowd of people who stood by and heard it were saying that it had thundered; others were saying, 'An angel has spoken to Him'" (my emphasis).
Did "the crowd" include the God-fearing Greeks? Was it a crowd of true believers in Christ? Was it a mixture of the two? Frankly, we do not know; moreover, the Synoptic Gospels do not give us additional information about the incident.
Regardless of the composition and demographics of the crowd, the Jews in the audience would possibly have associated Jesus' words in v.32, "And I, if I am lifted up from the earth, will draw all men to myself," with the story of Moses and the brass serpent in Numbers 26:6-9. Jesus also alluded to the serpent in his conversation with Nicodemus, recorded in John 3:
"'As Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up; so that whoever believes will in Him have eternal life. For God so loved the world, that He gave His only begotten Son [in death] . . .'" (vv.14-16a, my emphasis).
We cannot say for sure, of course, that Christ's words resonated within the heart of Nicodemus, let alone within the hearts of his hearers in the passage in John 12. Did the crowd associate immediately Moses' lifting up the bronze serpent with crucifixion? Even John the evangelist may not have known what Jesus was talking about when (and if) he heard Jesus speak the words about being lifted up, since his gospel was written years after Christ ascended into heaven.
Frankly, I think our search for an answer to your question has reached an impasse. Had God wanted us to know of a certainty that Jesus' audience for his remarks about being lifted up understood at that time the implication of Jesus' words, he would have told us. As things stand, we may need to leave your questions unanswered.
FOOTNOTE
Notice in John 12:34, the crowd evidently associated the phrase "lifted up" with death. Their words: “We have heard from the Law that the Messiah will remain forever, so how can you say, ‘The Son of Man must be lifted up’? Who is this ‘Son of Man’?”
The contrast inherent in their question involves the phrase "lifted up"--meaning death, and "remain forever"--meaning not dying. In other words, the crowd thought the true Messiah would live forever, but Jesus, whom they thought to be a false Messiah, was telling them in effect, "No, the 'living forever' part will happen only after I am crucified."
In living the Christian life, we know that our exaltation does not come before our humiliation, which involves a lifetime of dying to self as we take up our cross daily and follow Christ's example (Luke 9:23). We "humble ourselves, therefore, under the mighty hand of God, that in due time we will be exalted" (1 Peter 5:6).
