Mrs J
Your primary goal for the appeal is to show that you meet the criteria for an award, whilst issues such as spelling and poor grammar may suggest that the assessor was unprofessional in their approach to the review, highlighting these issues won't score you points.
Auditing is done by the Assessment Provider randomly unless the assessor was a trainee, it's possible that the Decision Maker would not be aware of whether this has happened or not, perhaps the DM was merely covering for information that they did not know.
It is certainly worth your mentioning that some of your evidence was not included in the review on the SSCS1, it is one thing for the assessor and/or Decision Maker to decide that a report or letter has no weight, it is another not review it at all.
But remember that the SSCS1 is simply to get your appeal accepted, it is definitely worth your waiting until you receive the DWP's submission before you make detailed arguments.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems