"Anonymous. There must be set down in a technique book rigid rules. If it says turn at the end of a step , then we are incorrect if we turn into the step."
This is a quite different issue than the subject of the thread, as the difference between turning into a step vs. at the end of it remains a difference regardless of how your orient the step in the room - it's fundamentally a different if you do it into or out of. However, many actions and figures now exist in two legitimized forms - a traditional one where CBM occurs into the step but the direction of movement is unaltered until a subsequent step, and a modified alternative with "curvy CBM" where the direction of travel is modified before the step is placed. I'd very nearly be willing to consider these two different figures, or at least two very different technical methods, and to be blunt only the first has any support from the technique books - but even that doesn't make the other "wrong"
"Point to me any step by any of our very best competitors where the would do a step that is technicaly wrong."
Leaving behind the curvy CBM issue, what they do is usually technically correct, but often markedly different than what is written in the technique books. This is because what they are doing is rarely exactly the same in important respects as the situation documented in the technique books, so applying the same basic rules of technique means that the actual details of execution will need to be somewhat different than given in the book in order to support the needs of the actual situation being danced.
Now as for the subject of the thread, the concluding orientation of an open telemark, the only thing that really matters is that the partners match each other, and have each part of their bodies in a relative orientation compatible with where they want to go next. Even if you name a direction such as diagonal wall for the movement, there's at least a 30 degree range of directions that can legitimately qualify as diagonal to wall. The real dancer will choose the precise direction that's best in the circumstances they find themselves in, reflecting things such as the size of the room, their position in it, other couples who may be present on the floor, and of course the overall shape of the line of choreography they are intending.