It looks like the issue is solvable post-build, someone fixed it by tinkering with the jar and some other madness here: Can't run Defold on my Server 2012 R2 machine (DEF-2105)
I got Defold to use 8u102 finally - unfortunately, the editor still refuses to recognize the DPI system settings and remains at a small scale. Is there some way to manually tell JavaFX to scale to a certain DPI setting?