https://www.reddit.com/r/RimWorld/comments/kmz0yk/i_tried_moving_a_river_with_devtools_and_despite/

Can the river flow map possibly be changed in any way? When placing sewage devices, the flow map overlay is shown (which is cool), but as I am using a map designer map instead of a vanilla map, the flow map is incomplete, and the water flow textures are kind of awful. Is there any way to somehow edit the flow map? I am willing to waste time editing the tiles 1 by 1, if only I know how to.