They spoke Old French, which had a decent phonetic orthography. Due to a series of successful spelling reforms, even modern French orthography is almost phonetic, with a few exceptions like Duras and fils, but the rules are complicated. English, by contrast, is halfway to hanxi — it's full of etymological spellings for most words, false-etymological spellings for a few, and a general spelling system that primarily reflects the pronunciations before the Great Vowel Shift. We can't blame this on the Franks.
Oh, I can easily believe the spelling made sense at the time. I'm not necessarily blaming the Franks so much as the English for hanging on to it. But you can't deny that words like "maquette" have French origin. (TBH I'm only taking it for granted that it has any real usage in English, but certainly words like it tend to be French. "-quette" is a dead giveaway.)
