CXLibrary has no repository nor issue tracking service.
The link that is given on the project site is blocked.
This effectively prevents any modder (such as me) from upgrading this mod via pull requests, since no source code for coremod of this mod is available.

@Filmos, just in case you don't get an answer like the other issues:
Try to contact the creator of this mod here (last active 4 hours ago): https://minecraft.curseforge.com/members/CubeX2
Or here: https://twitter.com/cubex2_

Thanks, I'll try that!

It worked, now the repository is public.