There are some issues in 1.14.4 release for MCreator 2019.5 that I would like to point out to let you guys know about for a future fix.
1. Dirt blocks don't generate under grass blocks.
I have tried to test to see if recompiling or building the mod would fix the issue and it did not work.
I have also tried updating the block element and the actual biome element but with no success.
2. Grass blocks spawn underwater.
This may be tied to the same issue above however the grass blocks should be dirt, not grass.
3. Caves don't generate in custom dimensions.
I then used to generate in 1.12.2 (1.9.1) however after updating the mod to 2019.5 it no longer generates caves.