Villagers will not autonomously get married nor have babies. Towns slowly depopulate via natural death by mobs/accidents. I eventually started using matchmakers rings to force marriage and they still will not have babies. Initially assumed it was a Config error (as I often edit config files), but behavior remained unchanged after regenerating config. Similarly assumed it was a population cap issue, so built 20+ houses, with only 2 villagers (1 male, 1 fem; matchmaker married) also yielding no new births.

MCA 6.1.0

That hasn't been readded yet

Any word when it will be readded? mod is kinda useless if villagers won't respawn.

Edit: And which version was it last working in, so I can use that one?

I don't know when it will be readded. You can use the match makers ring and give them a cake and they will have children. The last version it was working on was 5.3.1