I know a guy named Jonah and I've heard his mom call him Jones, Jonesy, and Joneser... but not Jonester lol.
I see what you mean about the "s" ending but I think of it as more prim than synthetic? Or maybe I'm just doing that American thing where I think it sounds British and assume it sounds posh just because I picture it in a British accent lol. Katz and Bex seem 'normal' but I'd imagine that William "Wills" got that nickname playing cricket at an expensive school or something.
I don't like Miles either but I like James and Jules well enough.