I played around a bit with stroke-based notation a few years back: http://archagon.net/blog/2016/02/05/rethinking-musical-notat... In theory, you could annotate arbitrary pitch-based music with this approach, even if it uses different tunings or scales.

If I have more time, I'd like to develop it into a more robust product one of these days—especially with things like MIDI Polyphonic Expression gaining traction.