Took me a bit to dig through the source code to find my answer. According to https://github.com/superpowers/superpowers-game/blob/v4.0.3/plugins/default/typescript/componentEditors/BehaviorEditor.ts#L206 the answer is...
No. Only boolean, number. string, and Vector2/3 are valid customizable property types the UI can display. The rest get silently dropped with a debug console error you can't see unless you open your browser console. (Can that even be done in Superpowers App?)
Disappointment.