We went through a similar migration process and it sounds like we had different experiences. We started with the devs taking some time just to study and learn

We went through a similar migration process and it sounds like we had different experiences. We started with the devs taking some time just to study and learn Scala basics then added the frameworks on top of that. I think if you go that way and you're using Slick > 2.0 it really starts to look like idiomatic Scala and everything in Slick looks like List manipulations. The other bonus is that a lot of the SQL generated perfors well and is easy to read.