I imported the SVG costume of myself from my computer and saw nothing in the SVG paint editor:
Yeah, this is a known problem. The vector editor can really only edit costumes created in the editor itself, not imported ones. Someday someone will get around to rewriting it. Sorry! Meanwhile, edit in some other program and then import it.
Off topic
Did someone modify this post to do this?
No, the forum automatically says that at the bottom pf most topics (it depends on the category).