See, even then they still had no concept about his Second Coming.
That. Does. Not. Matter. Jesus talked about it, anyway, because He was not obligated to talk about His future coming based on their understanding of it.
And no, I don't think Jesus' answer in Acts was misleading.
Of course it wasn't, but what He said wasn't at all what they were expecting and didn't line up with their understanding of the kingdom, right? Yet, He still wasn't being misleading. So, why would you think He was being misleading if He didn't answer their question about His coming at the end of the age in the way they might have expected Him to?
If heaven and earth didn't pass away, why aren't you keeping the Mosaic law? Jesus said it would not pass until Heaven and Earth pass away.
"“Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For I tell you truly, until heaven and earth pass away, not a single jot, not a stroke of a pen, will disappear from the Law until everything is accomplished" (Matthew 5:17-18)
Do you remember anything that people tell you? I already talked to you about this. That is not referring to the ceremonial laws of Moses. That is referring to the moral law of God. Surely, it's still important to not kill and not steal and such, right?
Look at the passage in context.
Matthew 5:17 “Do not think that I have come to abolish
the Law or the Prophets; I have not come to abolish them but to fulfill them. 18 For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from
the Law until everything is accomplished. 19
Therefore anyone who sets aside one of the least of these commands and teaches others accordingly will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven. 20 For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.
When Jesus referenced "The Law" in Matthew 5:17-18, He was talking about "these commands" that He referenced in Matthew 5:19. What commands were those? Ceremonial and ritualistic commandments found in the law of Moses? Clearly not. So, what then? We need to go back to what He was talking about prior to Matthew 5:17.
Matthew 5:14 “You are the light of the world. A town built on a hill cannot be hidden. 15 Neither do people light a lamp and put it under a bowl. Instead they put it on its stand, and it gives light to everyone in the house. 16 In the same way,
let your light shine before others, that they may see your good deeds and glorify your Father in heaven.
He was talking about His commands to "let your light shine before others, that they may see your good deeds and glorify your Father in heaven". He was commanding them to act righteously and obey God by loving God and loving others as He had commanded them to do. Remember, He summed up the entire law in two commandments: love God with all your heart, soul and mind and love your neighbor as yourself (Matt 22:37-40). That is "the Law" that must be followed until heaven and earth pass away.
Any time Jesus spoke of heaven and earth it was always about the actual, literal heaven and earth. He talked about heaven and earth passing away in relation to His second coming. Just like Peter wrote about in 2 Peter 3:3-13. Do you deny that 2 Peter 3:3-13 is about the literal heavens and earth, too?