I recently started using Joplin as a shared personal note taking application and saw that it supports something called ABC Notation. It's basically a markup language that lets you insert notation inline with text. I've started using it to make rehearsal song notes and it comes in handy to do little quick rhythmic or melodic figures and stuff without having to create an entire sheet of notation and export as PDF.
https://abcnotation.com/
(https://raw.githubusercontent.com/joplin/plugin-abc-sheet-music/HEAD/images/PeacherineRag.png)
I'm not sure how complicated it would be to add the functionality to Bandhelper, but if it was there, I would definitely use it (and I imagine others would as well).