No OP I meant elsewhere altogether - out of this company & in a different role utilising different skills.
If you know what your strengths & weaknesses are why remain in a role that it’s becoming apparent (either to yourself and/or others) that you’re not excelling in?
When you talk about your achievements in your side gig you sound much more proud of these & your ability to carry them out.
It sounds as though you’ve been allowed to try to be utilised by the other departments but as there is no budget for anything with them are going to be stuck doing a job it’s clear you don’t really enjoy or are especially good at.
I know it may be hard to accept, when you feel so clearly capable of better (?) things, but this role does not sound right for you.
You are very defensive about the feedback you’ve been given about your errors & performance. Which is never a nice process for anyone but is a necessity if you are to thrive in the workplace.
But instead of allowing yourself to be in the wrong about certain mistakes & areas you need to improve in, you’re trying to dispute & find fault with the process itself, and demonstrate that it’s their fault for not managing you correctly in the first place.
It really doesn’t wash to say “well you were happy with this standard of work before so why is it a problem now?” If that standard contained errors & was below what is acceptable.
Your arguing over the semantics of what “acceptable” means & whether or not anyone had ever pointed this out to you, is not helping your case.
Yes you need to know if you are being officially managed out, but there are some universally acknowledged general standards of performance, like basic grammar, spelling etc that are assumed & do not need to be literally “spelled out” especially in roles like yours, that go without saying.
Has anyone ever specified that you should be using English language in your documents? Otherwise does that mean it would be ok to use French? Or Portuguese or Latin?!
If you’d been writing your documents in French, but work for an English speaking company, with English speaking clients, would it be ok to continue using French & to argue that as nobody had told you this was incorrect to continue doing it anyway?
I’m afraid your argument is farcical OP.
It sounds as though you think these errors are not particularly bad & keep trying to apportion the blame for them elsewhere.
Surely you appreciate how the professionalism of the company is reflected in any of its correspondence?
Do you lack a basic appreciation of how important your admin role is? Are your feelings towards it being a lesser role than the side gig you so much prefer, feeding into your ability to carry it out properly?
I would not want to work with a colleague who does not have an interest in attention to detail if that was central to the role they were employed in. If they repeatedly waxed lyrical about higher pursuits elsewhere in the company, but were not delivering the basics in their given role, I don’t think I would be particularly impressed by them.
Your perceived abilities in a completely different area than the one you’re employed in & your attempts to turn their accurate feedback of you into grounds for an employment dispute is not helping your case OP.
Neither is trying to appear cleverer than or above the system & your seniors.
I doubt you will be able to accept any of this feedback but it would be wise & ultimately beneficial for your career in general if you could.
Learn from it & move on.
Good luck.