It sounds like you have a good idea of what you're doing with the switch. If you're doing web stuff I'd recommend checking into Elixir or Ruby, they are an absolute joy to work with and Elixir in particular is a very fault tolerant functional candidate. In my opinion Elixir has the greatest documentation I've seen of any language ecosystem.

Also both Elixir and Ruby I think will be syntactically closer to python than Go or Kotlin but then again you seem to know what you're looking for and you have to choose what you are passionate about.