A bit of background: I'm no stranger to BG2 modding. I've used Fixpack, Tweakpack, Unfinished Business, Widescreen mod. I installed all of these recently intending to do a playthrough of BG2 with my cleric/mage. While going through Irenicus' dungeon I noticed something disturbing. Chant was not granting attack bonus nor damage bonus. So I did more investigating.
Using Fixpack version 10, the files relevant to Chant were added to the override folder that modified it. After trying with and without those files, I determined that the fixpack provides a partial fix to Chant, in that it gives the saving throw bonus, but didn't appear to affect attack bonus or damage.
I should be more clear. I was looking at the character statistics screen.
So the next thing to do was to do some baseline comparisons of how the spell actually functions in combat. I went and started hitting a memphit with a basic weapon I have proficiency with, a warhammer. I found that I had +0 bonus to my thac0 without chant, and a +1 bonus to my thac0 with it up. So it does appear to be working.
TLDR: Why doesn't chant show the +1 to attack and +1 to damage in the character record?