I don't know about a historic source, but a few thoughts:
The reason to put the accidental before the note does make sense from a reading standpoint. Get the "warning" of the accidental first, then the note. Although it really wouldn't be too hard to read it with the accidental after, surely it's "read" as one visual "chunk."
There is non-notated usage "flat five", "lowered seventh", etc that prefixes the accidental.
The rest is just the craziness of the English language.
Sharp and flat are adjectives in basic usage, but they can also be adverbs, nouns, and verbs where to position before/after changes.
- ...start at 7:30 sharp..., ...turn down flat...
- the musical symbols, a sharp, a flat
- ...sharp the C..., ...flat the C...
The last example, the verbs, it strange. Normally you would use sharpen or flatten, but definitions for music usage give plain sharp and flat as verbs.
That is further complicated when using a past tense verb as an adjective:
- ...the sharped C..., ...the flatted B...
Sometime English places adjective after nouns, postposition, like in attorney general, private first class, eggs benedict, Generation X, etc. etc. There aren't clear rules for when the adjective comes before or after the noun. But, in regard to historic use, it's interesting that Wikipedia explains that the postposition is often an archaic usage.
The musical usage C sharp or B flat seems to me the postposition form, putting the adjective after the noun.