Asides from crashing when placing the water limit pipe, I don't know how you are supposed to transition from the otg (over the ground pipe) to underwater, if building otg pipe in a line up until the water limit and then building underwater pipes the rest of the way is the itended mechanic, well, it doesn't work. It simply fills the pipe initially and never updates the liquid level, basically akin to the pipes being connected for a fraction of a second only.
If you are to fix this mod, a good way to go around the transitioning from otg to underwater would be with a Pipe-to-Ground segment to an Underwater-Pipe-to-Ground segment. I think it would be a pretty elegant solution.
Another bug is that the underwater pipe is drawn over vehicles that pass over it.
Overall I like what this mod attempts to do and I wish it worked as intended.
Kind regards, Alin