Having read tome's comment above, I went and looked up "orthography". :)

Is there a word for ambiguity ambiguity? (i.e. Which type of ambiguity?)

Ambiguity ambiguity sounds like semantic ambiguity, but there are lots of different kinds of that. There's a book that disambiguates ambiguity ambiguity, by W. Empson (math geek turned lit prof), Seven Types of Ambiguity.

You just reminded me of why the Internet is an incredible invention.