So many terrain issues

I have been working with open world terrains ( something like 50 terrains ) for a long time and have encountered a large amount of issues that are driving me a little crazy.

  • Terrain paint details will randomly re-appear on terrains and appear on other terrains. ( lets say I delete Grass1 from terrain1, randomly Grass1 will re-appear on terrain1 or terrain 17 even though I never used that grass detail on that terrain )
  • Terrain paint textures will randomly re-appear on terrains and appear on other terrains.( same as above, can delete the texture or never paint on another terrain but will randomly appear on a terrain I never painted this texture on.
  • If a single terrain has too many textures or paint details, it will cause weird lighting issues on terrain grass and weird display issues.
  • If too many paint detail objects are on one terrain it starts causing atlas issues which causes random white borders on 2d/ 3d paint details grass.