Proudable doesn't exist at all, I'm afraid - it's a complete nonsense word. Nonsense words can't have synonyms, because they don't mean anything! Prideworthy doesn't exist either, but at least we have some idea what you are thinking of. There are some ideas which can't be translated by single words. I would express this idea in a phrase such as: He deserves to be proud if himself. Would that be suitable for what you want to say?

Agree with Su Ki... proudable would cause people to scratch their heads, "prideworthy" sounds like a word and would be understandable but it's not actually a word. So... you need a phrase to express your meaning. Here are a few that come to mind: "worthy of pride", "something of which you can be proud" (more formal) or "something that you can be proud of" (less formal)