Sorta, but on the other hand how can she know? The whole purpose of the Interceptor is that they CAN'T be predicted. They are outside Fate's weave. So perhaps she believes MC is important, but doesn't know for sure... perhaps because the Interceptor being active means time was reset, maybe SHE reset the timeline?
And then that brings to mind the question about how far does the reset go? Does it go all the way back to when Arceus created everything? Does it go back to when the Core was created? Does it just reset to when the user's life began? Can the user designate a time for the reset? Is it possible she performed the reset, and the armor is what's keeping her there and stable?
Also as for the Marianette bit it can still make sense, she only has brief interactions with your character, so while familiar it's not a lasting interaction AND also they have no idea about MC being the Interceptor, but what DID happen is that she's seen us at two very different stages of her life and we haven't aged at all between those two times. (I keep on wanting to put my MCs name instead of writing "MC")
Not to mention that she could also just be pretending to not know them... it's not exactly unheard of and has already happened in this story ('Nastasia and Ren) even though he's eventually sorta figured it out at this point she wasn't doing more than hiding with sunglasses.
Maybe she had no choice in the matter? It wasn't revealed if there's a way to strip the abilities from someone, or if there's potentially a way for her to lose them... and then there's the possibility of her having passed them to someone else for a different purpose (Such as when Melia offered hers to Nim).
I don't think it'd be Genesis syndrome as it has shown a 100% fatality rating from what we've been shown, which is heart-breaking for Melia's case. It said that internally she's already aged to what was it? 75?
I highly doubt that would be the case with Maria as she is a being created by the Archtype, where as I think Genesis Syndrome is from people being bestowed the power.
Logically speaking I think the highest chance is that either she gave the power away, (Perhaps to avoid some hidden effect we don't know about) got it stolen from her somehow, or she has simply taken extra steps to hide her identity by dying her hair. Though I suppose there's also the chance that the whole purpose of the suit, which has black shards as parts of the make-up iirc, is to keep her alive because of Genesis syndrome.
Well I don't think it's grounds to cancel the theory entirely, there are many possible reasons to want to experiment with this. If it worked then they could create more like him and open rifts in multiple places at the same time. Perhaps creating a clone drains something, be it life-span, power, perhaps it's why she lost the archtype power, assuming she is Maria.
Well for that I personally look at the destroyed timeline, there wasn't much of an issue with Melia and the Princess being in the same time for the moment, over time perhaps, but right then? Nah, nothing immediate anyway. They did state that eventually one would randomly be erased, which was why they needed to Overlap.
It makes sense, then starts making me wonder who caused the whole incident with the Ultra Beasts... because they specifically used Nihilego (iirc, I always get confused between them) which is a parasite that does the same, drains people of their energy.