PIP secret recording by 'friend' useful in appeal?

I helped a brain damaged man (R) at his DLA to PIP interview. I logged in as a 'friend' and gave a false name (I don't wish to be on their system) and also covertly recorded the interview (I do this a lot anyway as am very deaf). I see there are no recording restrictions or rules applying to a support person only the claimant. During the interview R needed much help with reassurance, memory, understanding, finding documents etc - at least 15 clear 'prompts' - and completely broke down with the HP saying the interview would need to end as he couldn't continue with the man in such distress. All of this is clear on the recording but none of this appeared in the report with the HP stating 'needed no prompting' and 'coped well'. I advised R that he must have passed the interview and believed this so - I'm shocked.
Although mental problems were the stated disability and R has a long term Psychotherapist the HP provided was an 'Occupational Therapist' (?) and although communication problems were stated the man did not speak English being first language Lithuanian. I couldn't understand him a lot of the time and I know Russian! You can easily make this out in the recording but no in the report of course.
It happens that I am a qualified in communication support (with BSL lev1) and so fit the criteria for com. support person ... this a stated need on claimants form ... it was 'needed' at the interview. Report suggests he didn't need help.
It's 4 months since CAB sent in his reconsideration request with no word - I expect this will go to appeal. I have provided him/CAB with a detailed transcript but just don't know if I should advise him/CAB to include it in his appeal evidence or to get a 'professional' one made. (I don't know if they sent it to DWP with the recon 'evidence')
I'll probably attend appeal with him as CAB don't do this and he needs the com support. But how much to make of this dishonest report - what should I say? (I see what Mrs Hurtyback says about not much weight given to them). Any advice welcome.