I just wanted to say I did a fresh install (SOA, TOB, Patch and Balderdash) but kept getting the error at the begining telling me I had not installed TOB update patch. Found that the file class.ids was missing from override and copied it and placed into override. But then game was unable to open HD0Gmosic.biff.
I did the total install 5 times and even redownloaded just incase I coruppted the program, then finally I thought maybe I am using the wrong Balderdash.
Yep I found the problem was I was using Balderdash-Weidu 1.4 which does not do anything to the class.ids. When I used the BG2TOBFixPack112Balderdash everything ran fine and game started. So it does matter which one you use.

I think the WeiDU version of Baldurdash is not completed as you have already seen. It really worthwhile to strickly follow the installation instructions:

SoA+ToB+Official ToB Patch+Baldurdash v1.12 for SoA&ToB

Then you may install NeJ2. I would strongly recommend to freshly reinstall everything this way in order to prevent further problems. I hope it won't take much time and efforts of yours to do so, and thank you for this report.