I am afraid I cannot answer the question concerning the publications (maybe if you send an email to the TO they clarify this point, usually they are rather quick in their answers), but I can share my experience with the language certificates (I passed the eligibility check):
As you, I had a relatively good level of French as a result of visiting courses and living in Brussels for a while, but I never took an exam other than A2. However, I did not want to say in my application that I had an A2 because it is not true and I wanted to increase my chances of being selected.
When the time to provide the documents arrived, this is what I uploaded for French:
- Certificate of my French school confirming that I was doing a B2 conversation course at the moment.
- Proof that I had registered for the B2 exam (and has paid for it) that was going to take place after the deadline.
In addition, I included a page where I explained this situation with things like "I have lived in a French speaking country and now I am committed to pass the B2 exam, etc etc etc". Apparently, they considered this to be suficient proof and I passed the eligibility check.