On the contrary, tie-in novels are always obligated to remain consistent with screen canon as it exists at the time, though the reverse is not the case, so they often get contradicted retroactively. Usually, in that case, new stories simply strive to be consistent with the new canon rather than the contradicted tie-ins, though sometimes they find ways to pretend that the old stories are still valid within the updated continuity, even if certain details have to be glossed over (this was often the case with the Pocket novel continuity during the run of Enterprise, e.g. when we had to reconcile the novels' portrayal of the Earthlike planet Andor with the canonical depiction of it as an icy moon named Andoria). But you're right insofar as that there was never a previous effort to retroactively rationalize older, contradicted novels as some kind of alternate timeline in the meta-narrative vein that DC Comics pioneered in the '60s and '80s and that other franchises have recently become increasingly prone to do.
To me, though, "resolving" and "reconciling with canon" seem like completely different things. Resolving an ending series should mean wrapping up any unsettled storylines that need to be wrapped up, answering lingering questions that were meant to be answered, that sort of thing. A series's completeness within itself is a separate question from its consistency with an outside series. I would've been happy with a final novel or novels that just settled outstanding loose ends like that.
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