I can take answer and then you can add if you feel there's something missing.
In some cases, in a drafting session maybe something will be noticed, and there's no authority to include that correction in the bill they're working on, so they might think it looks like it may be a candidate for the miscellaneous statute law amendment program. They communicate to the group responsible, and then that group will look at the proposed amendment and will have to get in touch with the department that's responsible. That's one way.
Sometimes it's found internally within the legislative services branch; sometimes it comes from different departments. It's possible that someone from the outside wrote in to signal an error they found in legislation and that message gets transmitted to the legislative services branch.
In terms of whether there was sign-off on these, yes, there was.