If a projects seems interesting enough for someone, it’s more than easy to see what language is it written in. BTW, that’s how things work: you don’t decide to contribute to a project because it’s written in your favorite language. You first have to like the project itself, and if it happens to be in a language you’re comfortable with, you may contribute to it.
Example: You might not be interested in writing a text editor, but you've seen this and the lime project, both written in Go, you don't care for writing a text editor, but you might figure you could spend some time to this guy fix an issue in your free time.
Is the above a little far-fetched? Maybe, is it unrealistic? Not really.
Still interesting tho.
Tools are a means to an end. Attaching anything more to them is silly.
I have a search set up that emails me daily about Clojure topics on HN. I'd be very interested to see new editors written in Clojure, and not very interested in using the editors themselves.
Both work well.