The problem with that train of thought is that it literally goes against itself.
Let’s analyze it.
The problem with version switching is that the codebase literally changes. The reason why greg and reika keep staying on 1.7 is because there is literally no other option, as huge code changes happen between versions. There is no other minecraft mod like them that has been updated for more than 6 years(!), and in fact, no mod at all that has been in development for that long, continuously, without a fork (change of dev[s]) or a large hiatus.
Even with all the time it took for the “big” mod version update from 1.7 to 1.12, gregtech 6 has been in continuous development between a nascent 1.7 and what is now 1.17. That is a fact.
Now we can clearly see that there is a circular problem here. Nobody will ever rewrite a proper port of GT6 to a higher version, because in 6 years time, people will tell you to stop updating for 1.17 (ew what an old version) and update to 1.30 minecraft++ xbonk limited platinum edition. Like you’re hoping exactly right now.
The whole point is that it’s a cyclic thing, really.
Also, good fricking luck finding someone willing to invest 6 years of his life in an open source project for his own enjoyment with the level of commitment Greg put into GT6 (looking very sternly at you, the mess that is GTCE) 