Is the term "Barrel file" somehow in common use? I've never heard of it (not a js dev though).
I would expect some kind of "umbrella file", "public interface", "reexport facade", or something along those lines.
Yes it's common terminology in the modern js/ts ecosystem.
It makes sense because your gathering modules into a single "barrel". We already have plenty of gang of four word vomit terms we don't need anymore.