The recorder of the name (likely to be attached to a religious house, but unlikely to be a 'priest' in quite our modern sense) wouldn't be changing the name (the child would still be called Amand), just the recorded form. Which he would record in the Latin feminine because the record would be in Latin and the child would be feminine, no other reason.
And educated parents would be fairly thin on the ground, verging on non-existent, in 1200ish. Educated monks would be more likely. I think the male name is most likely here.