Most paleographic description that I’m aware of (not that there is much) has focused on the description of letterforms within markup (“high ascender”, “round”, etc.) and not on tracing the forms themselves. Aside from Vindolanda, of course. There’s a lot of work to be done here on the encoding side – TEI really doesn’t do well for paleographical description, and I haven’t really seen any extensions that satisfy me (as I say, not that there are many). I know this doesn’t really address your question, but the general issue is an important one and I only wish I had more time to think about it myself.