Not in my experience. I once helped build a team of Elixir developers. There were few people who knew elixir at the time. That simple filter ended up getting us a really great team-- much better than interviewing a bunch of applicants from with other language backgrounds-- the people who wanted to learn elixir, knew it, or were interested in it, were much better than average.

In fact, that's the only effective filter I've found for interviewing.

Our evaluation of "smart" is independent of syntax absorption. It's less that we convince them to absorb a different syntax, more like we select for people who wouldn't get hung up on it.