I stupidly built a product with Svelte and I certainly had a "focused pool of candidates" -- no one at all with experience using Svelte.
At Basho, we were happy to hire people without Erlang experience as long as they had FP skills.
Yeah, I definitely don't care what backend language experience someone has before hiring them.
I haven't had the same luck with frontend. There's so much magic, config file hell, and other rough edges that you need someone who knows the framework. In the JS world, actually writing code is maybe 50% of the work, and managing the ecosystem (config, build, packages, etc.) is the rest.
And you’re doing a grave disservice to Elixir at the least. I prefer Erlang myself, but Elixir has established itself as a robust choice.