Generally speaking (since this tends to come up every now and then) for this kind of stuff you’re better off making your own changes to the game and, if you’d like, share the script file for everyone to use.
All the relevant recipe additions/edits in your bullet points can easily be fixed with applying custom scripts with https://www.curseforge.com/minecraft/mc-mods/mtutils, which has GT6 support and is fairly easy to understand and write for without any sort of coding knowledge, the github has a wiki, and if you’re swamped you can just look at a few examples from modpacks which already have GT6 scripts (terrafirmarescue’s github page does actually come with its own extra page of information on how they work, even).
The only thing it can’t do is 8.