Patch 1.6.1 for the original campaign.

Great! Have you checked if it works on version 3.1 with the mod for the original campaigns?

I haven't checked, but it should work in theory - the Nival Interactive team didn't change the scripting system in 3.1, they only added new functions, the document structure remained the same. But I wouldn't recommend playing with version 3.1 - it has a different progression, and I overwrite the skill file because it contains priorities for the AI, and I have no idea what that might lead to. It's better to create a separate version so that Markel can throw mass vampirism at hardcore fans 😈.