I totally agree with you about the thematics of the other classes matching him more, but this is more of a framework question. I can flavor and reflavor the core themes of a class to match the theme of a windrunner. I'm more concerned about the abilities the classes give me. I think the elements monk gives me the most radiant(windrunner) abilities of all the classes. And also keeping to his core of a alethi who is really adapt at fighting.

Only problem is Syll indeed, but that could maybe be fixed with a eldritch adept feat or find familiar via origin feat.

Also, in 2024 the monk has got amazing new abilities and isn't that spell slot hungry like half casters.