The big question that will affect everything here and thus needs answering : what about the compatibility of the underlying physics? This includes everything derived from it, thus chemistry, biology, those things. Also things that doesn’t exist in one world but does on the other, such as Arts.

Whether or not Originium can spread to our world. Whether or not we can use Originium as energy source. Whether or not our fossil fuels work for them. Whether or not we can use Arts like them. Whether or not they’re susceptible to our diseases, the list goes on. And if there’s any discrepancies/incompatibilities, how it’ll work across the gate. All those things will affect how we interact with them, and how that interaction develops.