Isn't it funny, I have never heard of the saying, "Be happy in others' Success," before today. It's a nice little saying. I don't know that it would be something I'd want to live by though.
Your take on it is much better. Perhaps yours would read, "Be happy in others' success once you're happy in your own." It's much more comfortable that way. You're less likely to feel bad when feelings of envy or resentment surface because happiness comes when you can accept and appreciate your own bounty first.
Ah, well, that's my twopence worth. I hope you're enjoying your Hive experience so far. 💛