You are supposed to get that advancement by breeding any two animals. It seems to works with other modded animals (like snails from autumnity of foxhounds from quark) but not with the booflo.

Known, and won't fix. Booflos are not considered animals in the code since they have lots of unique data to them, and to conserve data usage they were split up into multiple entities. I won't go into the full details, but this won't be fixed, it's intentional.

It works with Puff Bugs however, that is because Puff Bugs don't have multiple life cycles and we don't have to conserve lots of data

Wow, I had no idea it was possible to breed puff bugs. Thanks for reply.