I assume by "non-native", you mean "non-idiomatic"?

Since I recently went through coworkers writing "bad" (by which I mean non-idiomatic) Scala, and repairing the situation, I can say that it was surprisingly easy to lay down "functional constructs" and the result was amazing. The code became reliable, well-structured, and easy to leverage. Switching to Scala for our projects -- including introducing procedurally minded programmers to it -- was a huge win for us.