After a few hours of reading and re-reading Bennu code and even reimplementing mod_proc, I think I finally fixed the regression in mod_proc that caused signal not to work.
This was a stupid bug. It was caused by me not knowing well enough how C works. Should I have read and understood how enums work in C, I wouldn't have redefined some internal value that told Bennu to kill a process when told so (I was instead messing with some other internal var).
Well, I just wanted to let you know that I think I fixed it.