So the real question here is:
“I have the rights / permission to use the IP and I have the official assets. Can I make cinematic sequences out of it using UE4, and monetise them?”
I think that should be doable but it would be best to ask Epic directly. Not sure how they feel about you importing assets from another engine (?) into UE4.
In case no Epic staff shows up to answer it here, consider dropping a message using this:
I think that should be the right place.
Would this be similar to Mojang and Telltale collaboration, where they created Minecraft: Story Mode using Telltale’s in-house engine?
You better get a lawyer 
It’s serious business!