Switch may support UE4 but that doesn't necessarily mean anything running on this engine is an easy port. Hellblade is still a demanding game that's 30fps even on PS4 wasn't designed with the limitations of a mobile SoC in mind.
And we don't know how it overall runs on switch yet either.
Nonetheless, if it is ue4, it is always possible and not surprising. It's not easy of course but it's alot easier than porting a non ue4 game.
Anyways DQ11 is ue4 and I'd argue that would be more difficult. Hellblade is a very linear experience.
I honestly think you are overselling what this port means.