Some experience to share: I studied Scala and FP on the side before jumping to a team that was using it in production. Most of the engineers on the team have an enthusiasm to learn about and use fp.

Bi-weekly we have a book club where we take turns presenting a topic from functional programming in Scala, functional reactive domain modelling and others.

We program as simply as possible but when a new technique is discovered we go ahead and use it after it's been presented to the team and everyone is comfortable with it.

all code is reviewed and unreadable code does not pass

Compile times haven't been an issue. As an example a 100k line Scala program with around 900 files takes around 2 minutes to rebuild whilst incremental changes are immeasurably fast. Reloading code while a local server is running is easy by default in IntelliJ.

Using worksheets for playing is often useful.

we don't use actors where streams would make more sense and vice versa, know the purpose of your tools

I've had bad experiences with Go. I know that for the application I'm working on it would not scale to 10 programmers working and constant refactoring due to business goals changing.