Two things I need to get sorted out for the plain text drum tabs are accents and buzzes. I did a little soul searching and digging around in Unicode.

Accents are easy to do with inverted breves from Slavic languages.

L̑ (U+004C with U+0311 - combining inverted breve above)
Ȓ (U+0052 with U+0311 - combining inverted breve above)

For buzzes I realized that if I do them, they are natural so I probably don't need to clutter up the patterns. If I really need them in a pattern, I can type a note about it under the pattern, for now. This could change in the future.