Well, I made it (seems an earlier attempt to join did work) so I can reply in person
I'm not entirely sure what you mean by "codified meanings", but I assume you are suggesting some sort of fixed interpretation. Well, speaking as a mentor on the TABI endorsement scheme, we certainly have nothing like this. In fact, quite the opposite - we actively discourage regurgitated interpretations and plagarism is not tolerated. I can't speak for any other organisation.
All mentors have themselves been through the endorsement process and, for the record, it's not just newcomers, we have have tarot teachers, published tarot authors and some very experienced readers go through the scheme. Where possible, given that it is all voluntary, we try to pair applicants with a suitable mentor, based on the information given in their application, so Thoth-ites will be paired appropriately. We rarely accept total beginners, since endorsement is not intended as a training scheme - we run a free beginners course to cover that - but encourage them to reapply when they are more confident regarding card meanings.
As a mentor, speaking personally, I offer guidance and advice where requested, the benefit of my experience as a reader and reasonably coherent writer, and I expect life experience comes into it too. I only question interps if I can't see where they have come from and then I will ask for an explanation of the reasoning, rather than dismissing them out of hand. I will also often offer an alternative view for the reader to consider on an interpretation, but this is not compulsory for them to adopt, just a comment.
I, and most, if not all, my colleagues in TABI would agree that we do not know everything there is to know and one can always learn from another reader, regardless of whether they are more or less experienced. So just because someone does not agree with our interpretation, does not necessarily make it invalid. However, I think you will agree that if I get an interpretation of, for example, RWS 10 Swords that suggests the querent will live happily ever after, or equally that they are about to be stabbed in the back by 10 of their mates, that I would be justified in considering this unacceptable for a number of reasons
In this instance, I would insist that they revise the reading, giving my reasons, but I would not tell them what to write as it is not my reading.
I can't speak for all our mentors in terms of menotring style - we do rather trust to their judgement - a position that I feel is justified by knowledge of them as readers via the endorsement process. Though we operate a peer group for mentors too, both for support and as a progress check on how they and their mentees are getting on and mentor feedback form. We also have an (infrequently used) mediation process and a "no-blame" process for mentees (and mentors) to request a change if they feel they have a problem with one another, though we do encourage them to resolve their differences as these can often just be down to misunderstanding - easily done in a cold medium such as email.
If you need to know anything else, I suggest you apply and find out for yourself :-D (Though please don't apply unless you are serious. We are voluntary and having our time wasted is demoralising)
regards
Ania
