Hi! As I tried this mod, I found out that decorations such as grass remain when water is placed, meaning that I for example may have to place down and then remove entities or other tiles beforehand, in order to get rid of those. If you want your mod to do this automatically, just add this line in the item-related lua-files:
data.raw.tile.water.decorative_removal_probability = 1
I have already tested it, and it seems to work without issue.