Also, I don't know if this is helpful or not, but I saw in the log something about repurposed structures, and after disabling that mod the game crashes with the same exit code but a different error. The game crashed: exception initializing level Error: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
https://mclo.gs/i8bD1mD These are the logs from that crash.
Also, after removing fossils and arch, related mods, and repurposed structures, it gives exit code -1 and this crash report https://mclo.gs/hv8brA6.
Again, I don't know if any of this helps, but I greatly appreciate what you've been doing. If you think the pack is just too broken in general I could also just try to remake one step at a time.