Samuel,
You really do not have any problem at all.I will advise you wait till you receive your PER before you send a cover note to accra with the updated form. Although, they may also request for the same form at first sight as well. However, i will advise you holla them immediately you receive your PER before it gets to MR stage.
I will not advise you write sydney now because of the large number of applications they receive, the ability to respond to your request on time and also to scale the initial completeness check over there. The issue at hand is a common norm that perhaps known to them having such minor errors occurring in applications though some people purposely think they might not know.
I know your heart is up there because it is not easy all. I passed through a similar scenario and i can assure you that you will get in IJMN.
Just pray for favour along with your application.
Regards,
Poldy.