Same here. i'm searching for an answer. I'll let you know if I find one

I found the answer on my own. It's easy to fix if you have the tools. You'll need Pack File Manager to open the .pack file.

1. open _new_open1100.pack in PFM which is the Part 2 mod pack

2. delete the files for "character_skill_node_sets" and "character_skill_nodes". They are entirely unnecessary files as far as I can tell with the vanilla game files being nearly identical so it seamlessly takes over. The mod's version of the files appear to have errors in them that breaks the army traditions mechanic. This mod is amazing but it seems to be really bloated with a lot of unnecessary files that makes it more prone to bugs and crashes. The vast majority of mod's files look to be identical to the vanilla versions which makes them absolutely unnecessary and frankly kinda stupid why they're even there. Any modder for this game should know that they don't need them, even for a mod this big (from my experience, pretty much any game wouldn't require you to build even an overhaul mod like that). The game will obviously automatically fall back to the default vanilla files. This mod could do with some serious trimming evidenced by the fact that I deleted two entire files and it actually fixed it, and I'm sure there are others (I've been customizing the mod extensively to my own taste and noticed this as I've been doing it).

i will look into that thank you!