What I was getting at was "The Romandie is what the Artiste accordions should have been but aren't: a CBA Morino with cassotto.". That statement applies to the 4-reed instruments of the Artiste N and Artiste S series. The overall geometry requires putting the lowest reed block behind the keyboard, and not placing a déclassement there ruins the consistency of the sound across rows.
The original design made sense, so the "should have been" comment turns me defensive against the creator of some of my instruments. That the déclassement was discontinued likely had separate reasons: the whole point of moving fabrication to Excelsior was to employ their different in-house expertise except for the optics. That led to heavier instruments. They probably had no dëclassement specialists, and the dëclassement is problematic for servicing since it is assembled before its load-bearing part of the case is glued into the rest. Replacing pallet felts is close to impossible.
So there may well have been good reasons for Excelsior to say "I am sorry, Matthias, but I am afraid I can't do that". But that doesn't mean that the original Artiste D design was wrong or inconsistent. Just that it transferred worse to Excelsior than other elements.
There would have been a point in offering the Romandie
instead of the Artiste VI N (the latter incidentally also has a smaller range than the Artiste VI D). But that might have made the outsourcing more obvious.
However, I'm not so fond of the H reeds in cassotto. They don't stand out enough to for instance make MH sound interesting and noticeable different from just M. Some accordions have just L in cassotto and all M's and H outside. I can see where that may work better.
That would have been my guess without having had actual experience: the point of an H reed set is to add overtones, and the point of a cassotto is to reduce overtones. It sounds like that would make for a comparatively subtle difference M/MH particularly if M is outside. But I find that one feature of multiple reeds is to make the sound more "pliable": I find that a double reed reacts considerably more lively to pressure differences, possibly because they tend to have different pressure responses. This difference may be mostly lost to listeners, particularly in an ensemble setting, but it does something for me as the player, and stuff that the player hears or feels makes them indulge and that rubs off on the audience.
So I could imagine that a H reed in cassotto might help with that. If it does, that could provide
some justification for that arrangement. I really need to spend a lot more time with a lot more accordions...