And how does it differ from the new version?
I couldn't say without knowing how old your version is. But frankly, I don't care to support old versions. If you want to use it, you are mostly on your own. Oh, yeah, no support is another reason not to use non-standard versions of standard functions.
The particular error you posted happens because sc#addWmpAre is trying to patch saved games (inclSv is not set to 0), but BG2: EE keeps its saved games elsewhere and no directory called "saves" exists. You may as well set inclSv to 0, because patching saved games is a bad idea and sc#addWmpAre can't patch EE saves anyway (because the EEs move the saved WMP into the SAV file and I haven't updated the latest version to be able to unSAV the WMP yet, because patching saves is a bad idea). I can only guess the function was not trying to patch saves when you used it before, or you did not use it on BG2: EE until now.