Just randomly but are you aware of what 'malakas' means in Greek? I kind of don't know if this is a joke name combo because of that because combined with Prosper and Charles and then Malakas it could mean a kind of funny/crass phrase.
I only ask about the meaning because it is the one kind of swear/slang word a lot of people pick up from visiting Greece and it is one I use a lot myself as I have Greek family. Basically, it maybe isn't a good idea if you ever plan on having a son who might ever travel anywhere and have his full name read aloud by anyone with any knowledge of Greek. I know you're not planning on having more kids but still :)
https://en.wikipedia.org/wiki/Malakas