Ok, version 1.83 of the toolkit has been uploaded by Epic to the launcher. This version works with UE4.20. Check my last post for a description of the changes.
I’m not sure I fully understand the question. Do you want to spawn decals when clicking a tile? There is a function for that in BP_GridManager called SpawnTileMarkersAtLocations you can use for this. I don’t understand what you mean regarding having a unit already on a tile and changing the turn. Are you talking about teleporting a unit to a tile and then ending the turn? Could you please explain a bit more in-depth?