I wanted to take this up from a purely technical point of view.
When we get a UK refusal, we like to make the OP insert their refusal formulae. This is a formal notice from the UK government that explains the decision.
Without going in to speed codes and the mechanics of why the text is useful, we can turn to the relevant text for DJClayworth's question above...
I am therefore not satisfied that your application meets the paragraph
We'll forgive the OP for her mild transcription error and focus on the A57D(b) part of the sentence.
We observe that refusals falling within TSE's domain cite Appendix V of the rules (like when you see V 4.2(a) for the reason). Those questions belong to us because Appendix V contains the visitor rules, which is our turf.
Paragraph A57D is in Part 3 of the rules, which deals with short-term students. Different underlying principles, different assumptions, different semantics, different topology from visitors. Moreover, there is no terminology in the rules where 'short-term' is applied to visitors other than a short-term worker replacement and then it is to explain that a short-term worker replacement is forbidden. 'Short-term' is used exclusively for students and workers.
So by all rights and privileges when a strict technical standard is applied the question belongs to Expats.
The ECO said she was a student. We get visitors, Expats gets students. Trying to carve it out by visa duration will get unbearably murky.
The OP resubmitted her application before anyone answered her question. She got some help in the chat room for her cover letter etc. I was advising her to take a week and get a consultation/doc check before resubmitting, but it was too late. Refusals are emotive and back-to-back applications can often make matters worse. I doubt that answers from either TSE or Expats would have changed the outlook significantly, but perhaps her cover letter will carry the day. Props to @hippietrail for that part.