I requested a feature in this thread, that would take care of the problem: https://forum.renoise.com/t/note-align-sample-hit-point/32368 . I can’t really see this happening though, since Renoise seems to have gone in a different direction since I posted this.
I looked through that thread. I think I might try setting the vocal track delay at -1/8th of a beat, and then adjusting all of my vocal samples to have their beats hit 1/8th of a beat in. This should probably work ok for the samples that are already fairly well aligned.