It seems that the mod is dead. The author was last online in may of last year, and no activity has been indicated since, there is no github or other such means of checking progress either. Unsure of how the licensing and stuff would work at this point, but there arent any other skill mods like it, it handles balance in a very unique way and it would be sad to let it die out. Mod link: (https://www.curseforge.com/minecraft/mc-mods/flexible-skills-mod).
Any info on alternatives (aside from Goki Stats, PMMO, etc. I tried those) would also be greatly appreciated.