Consulting Robert Young's Literal Translation, in conjunction with his Analytical Concordance, I would present these points of interest.
He literally translates Matthew 24:34 & 35 as, "Verily I say to you, this generation may not pass away till all these may come to pass. The heaven and the earth shall pass away, but my words shall not pass away."
I've included verse 35 as it continues being consistently literal when interpreting the Greek words in question. Likewise with Mark 4:17 - "and have not root in themselves, but are temporary; afterward tribulation or persecution having come because of the word, immediately they are stumbled." Note how a shoot may arise, but turn out to be temporary, wilting? That's significant for the purpose of Mt.24:34.
In all instances, Young's translation shows that something is present. There is no hint of a process, even though what is present may continue for some time. It is evidently there and is being experienced. Something has come. Of course, that does not rule out a period of time wherein those things are present, but the phrase "all things" in Mt.24:34 indicates that it's not the start of various things arising that is the point. All things have arisen within a particular generation.
Interestingly, Jesus says that when wars, famines, pestilence and earthquakes happen, and false Christs arise, "the end is not yet"; that those things are but "the beginning of sorrows" (vss.4-8). There are more things to happen within one generation than that. More spectacular things will happen later, including the proclamation of the gospel to the whole world, to all nations. Perhaps that will happen the way Revelation 15:6-7 depicts, via an angel flying in mid-heaven (not necessarily literally, but by some means ordained of God). This seems to mean that the generation Jesus speaks of, the one and only that will see his spectacular return, see all those things happen. They all come together within one generation, unlike previous generations that saw some signs, such as false Christ's arising, wars, famines, pestilence and earthquakes.
That is why Jesus said, "this generation shall not pass away until all these things be fulfilled." There is finality when all those things combine. They have arisen in the past (indeed, what generation has not seen most of those signs to some degree or other?) but the one generation he identifies as witnessing his return will have witnessed more than that. They will be able to testify that they have seen fulfilled all these things, not just some of them.
That is why it had to be a future generation Jesus spoke of as being the one to see his return. The people he spoke to back then did not witness the combination of all the signs associated with Christ's return. They saw the arising of many signs, but there has to be a final, unwilting culmination of all of them, within one particular generation. For that reason, Young's literal translation seems to do justice to all the nuances involved:
"Verily I say to you, this generation may not pass away till all these
may come to pass." Matthew 24:34
This answer is sorely lacking in explanations of Greek words, but given the subtle distinction our Lord made between various signs arising, and a culmination of them along with more spectacular ones (like global gospel proclamation, and his chosen being gathered together from all over the world, vss.14 & 31) 'come to pass' is clearer than 'all these things arise' because things can arise only to fade away then arise again. Not so in that unique generation.