It's also pretty accepted among modern scholarship that during this time period willing eunuchs were essentially trans women, many prominent ones referred to themselves in the feminine and wore feminine clothes. Especially in the levantine context of the bible. See the galli of Rome, and the related Roman Emperor Elagabalus who is often considered a trans woman. She was from Syria, which Romans considered effeminate due to the prominence of 'eunuchs' in their temples, and Elagabalus was a high level religious figure in pagan Syrian religion.

Obviously the Romans saw feminity as weak and lesser, and would castrate enemies in order to essentially force them to be socially "trans". It's possible that Elagabalus was being smeared by political enemies as trans and too effeminate, but this essentially validates the theory that eunuchs were likely mostly trans women during this timespan. Plus, it just makes sense in lieu of hrt trans women would pursue castration.

Because eunuchs couldn't have children, they were often considered more holy in religions of this region largely because they didn't have any attachments to feudal and prefeudal relations, which allowed them to be impartial observers and advisors. This carried on into the middle ages, though the way eunuchs operated and were perceived changed dramatically as Europe christianized. They were generally respected by kings and queens and were given extensive education in most societies of this time period, so it's likely any literate scribe would know a eunuch if they weren't one themselves.