Ah yes…the mod question 
So the deal is this (per the license),
However, the Product may not consist
of or contain any Engine Tools nor
provide functionality allowing the
creation of standalone products
utilizing the Licensed Technology;
So - you may not distribute our tools (modified or otherwise) with your game. But you I have two ideas,
- Make your own simpler tool (with UE4) to make an editor designed to only make maps for your game. In all honesty you’ll probably want to do that. It will make it far simpler for users to make maps
…