Looks like they might have had a halfway rational system of writing and spelling at that time. I’m convinced English inherits its fubar spelling system from French.
old english was pretty rational as well. While a lot of our silent consonants weren’t silent in the middle english period and from what I can see consonant use at least resembles how the word was once pronounced, the absolute lack of any vowel-use norms makes english vowel pronunciation as much memorization as anything for many cases.