Month names collection / metastudy

[Bernd]

Actually, now that I think about it, surely the professional writers creating these expensive, luxurious books of hours were amongst some of the most highly educated and highly trained people in europe?

No, not necessarily.
They were employees of large workshops. Craftsmen, artisans. Not scholars. They excelled at what they did (writing, painting, creating layouts...) but that does not mean they had education beyond what was necessary for their task and they really understood what they were copying. The language, but not the deeper meaning. We frequently see hilarious blunders in high-profile works like using the wrong stock imagery for a plant. In the end it mattered little because the buyer was no scholar either.

In this context, I'd say it depended on the character of the scribe whether the mindlessly copied what was there, or added his own interpretations and possibly (hyper-)corrections.