The .xlsm files do not matter that much; by themselves they have 0 impact on the game. It is the Generated stats that come from those files (in Public/Main/Stats/Generated/) that really matter.
You might find it useful to look through my Tutorial thread for general main campaign modding info-
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=529996#Post529996That being said, unfortunately the TreasureTable is one of the things that I have not seen changed successfully by anyone. I haven't been able to do it at the very least. Any changes to the Generated TreasureTable file are ignored by the game, and I don't think I've seen anyone make their own TreasureTable file for the Main campaign and get it to work.
The best that I have been able to do is change which of those defined treasuretables are used by a certain entity in the game, as well as modify items so that they are part of the randomly-picked pool that the treasuretables instruct the game to give to the NPCs using that treasuretable.