Advice for painting a glass lampshade please

I have a vintage lampshade for my dining room. It was cracked when we bought it and there is a little piece of paint missing on the rim. We have strengthened the crack with glass glue and tbh it doesn’t notice much when it’s up, but I’m wondering if I could disguise it further with a stroke (or two !) of black glass paint. I could fill in the missing paint with black too, I think that would tie in with the other blobs. I’ve never painted on glass before, so wondered if anyone has any suggestions what to use or other advice. The shade seems to be painted on the inside. Thank you.