I believe the 1.2 is a typo.. I'm not aware of box2D lights have a version 1.2 as of yet, unless it's coming and they pre-emptively had it put in ahead of schedule to be called instead of v1.1.
For my eclipse build, I was able to compile it after changing all references of 1.2 to 1.1, and my gradle built just fine.
The setup worked even though I got those errors when using the gdx ui provided for the gradle build.
(at the very bottom of your gradle file, I noticed in the :core area, you still have a reference to boxlights 1.2, which you should change to 1.1)