I don't have it in front of me, but my recollection of reading Justice Mahon's book 'Verdict on Erebus' is that the official transcript was made when the NTSB played the tapes in Washington and that at the time, the RAE's equipment at Farnborough was superior. Mahon & Mr Baragwanath (counsel assisting) played the tape there and it apparently gave a different slant on things.
As for the 'Bert' comment, this was apparently unclear on the tape and they were unable to establish anyone named Bert on the flight, especially amongst the flight crew.
Mahon's account is of people sitting listening to the tape, manuallytranscribing what they >>think<< they hear - possibly making what they think they hear, fit what they think they know about the circumstances. I think he also mentions the possibility of some words getting mixed up due to differences in pronunciations between Kiwis and Americans.
I'll try to remember to take a look tonight & maybe edit tomorrow.
TD67.