I just don’t really see it as a contradiction. *shrug* All I see in this situation is Snow being completely lost for any other option, so she’s clinging to faint hope that maybe something can be done with the wardrobe because it’s the only thing she knows of that’s been a portal between those two worlds before. If I were in her position, I’d have thought the same way, get the thing that was the portal and hope against hope that you can make it work somehow. Was a better plan than just sitting on their arses or wandering aimlessly hoping to stumble on a working portal by chance.
We don’t know whether or not anyone in FTL history attempted to recharge magic. Maybe they did, and failed. But I don’t think that needed to be shown. We can just assume it wasn’t possible, because if it was, Blue would have been going around recharging stuff left, right and centre, instead of being bummed about having a limited resource of magic left in the world.
Also, if that was possible in the past, well, we’d have no show. So I’m happy to just accept that it wasn’t ever a viable option in the past, and that in the present day, Snow was merely grasping at straws to find a way back to SB.