This is the slightly stained Jinhao Shark I cleaned last week. I'm guessing those are actually tiny cracks/fractures in the section that got filled with Yama-budo while I was filling it initially, or something leaked after. I can't feel those cracks with my fingernail or otherwise, and it wasn't leaking before I cleaned it, so it's probably still fine for now. Even if it's not, Sharks are ~$1.70 each so it's not a significant loss.
Another interesting pen cleaning result today. I flushed out a Kakuno I had inked with Monteverde Permanent Document Blue. Everything was stained by the ink. The converter, the section, the feed, even the metal on the back of the nib itself. Maybe with some more effort I could clean it out better but I use blue inks so much that it doesn't seem like a real problem.