For those who don't know, Thomas Aquinas has a reputation of having tricky to read handwriting https://www.reddit.com/r/latin/comments/mbbjcw/this_is_said_... (I remember trying to find some description of his shorthand/writing style, but couldn't find anything - people love talking about how hard it is to read but never try explain how to read it...), but more generally medieval manuscripts have a large number of shorthandy abbreviations which throw up lots of problems for naive OCR-ing/reading, even if you know the language in question.