MBM have picked up on a point that might seem just a procedural detail, but is actually quite important.
With these pre-appointment hearings, IME the committee invariably publishes a formal report. Sometimes the report is even published the next day. It will include documentation provided by the government (the role description, the candidate's CV) and note the committee's take on the candidate's evidence. Usually it just says "we were impressed by the candidate's experience and are happy to endorse her"; sometimes it might raise concerns about the candidate, about the running of the recruitment campaign or about some issues the committee has with the body in question.
No report has been published, and it doesn't look like there's going to be one. The letter is all we've got. I assume this is because the report would have required committee members to go on record as endorsing or not endorsing the candidate, and they weren't unanimous; more importantly, it would have required the committee to show their workings and spell out exactly what their objections were, by reference to the candidates evidence.
They haven't done that. And, as MBM point out, they've produced instead this very allusive letter that dances around the issues that were very obvious in the hearing. I assume it took a lot of diplomacy to get the letter together, not just because the members weren't unanimous but because they needed Lord Alton's signature, and Lord Alton believes in God and has a strong aversion to lying.
I think it's extremely likely that Bridget Phillipson not only read the letter but also watched the hearing, and was not impressed.