I'm unable to find anything about teaching Repl.it how to understand / handle a new language. So, I only see Repl.it as useful to this process _if_ you're boots

I'm unable to find anything about teaching Repl.it how to understand / handle a new language. So, I only see Repl.it as useful to this process _if_ you're bootstrapping from one of the languages they already support... However, if you're bootstrapping from some other language you probably have better support for it and its libraries on your home computer. What am I missing? How is Repl.it notably useful to the process of creating a new language? It _seems_ like this is more of a "you can do it in the cloud, but not quite as well" kind of thing.