Rumors? I thought it was fairly well accepted that Cheng Ho made it to the West coast of Africa. Sounds like someone is trying to turn a standard story (they found a coin from the voyage) into something sensational.
Having said that, the story of his voyage and the size of the fleet and ships themselves are sensational.
In my short lived part time job not long ago we had lots of young kids ( 7-16) come into the shop. These were kids who had interest in history, coins, science and so on. One of my favorite subjects to clue them in on for study was the Chinese treasure fleet.
Most of the kids were regulars and you should have seen how excited they were the next time they visited. Being a history geek and discovering something you’ve never studied before is such a joy.