I believe, there's supposed to be a plus (+) at the end of the line?

might be mistaken - I believe, there's a comma missing between "ongoing" and "this"

Suggest rewording into separate sentences, i.e.
Previously, drivers were committed to FreeBSD src.git; they have now been retroactively imported into vendor branches and merged to main.

might be missing a comma here?

should this be "a half" instead of "an half"?

assume this means "unnoticed"?

I assume there should be a comma before "which" and one before "received"?

(g) is missing in beginning

I reworded it a bit differently. See if this is better.

s/works/tasks/ maybe? Otherwise clarify.

Spelling.