By the way, parts of the path along the Lark were heavily flooded; I had to take my shoes off

Yes, the former path is no longer accessible; a concrete wall is blocking it on the NW side, which I drew on the map. From the SE side one can enter the area but the path is fully overgrown.
There were some sort of signs along the new route, but I don't remember any details. I suppose they were not official.

Het pad is door de terreinbeheerder beplant en afgesloten. Er is dus geen pad meer; dat wou ik aangeven maar misschien was dat niet duidelijk. Heb er abandoned:highway=path van gemaakt; is dat beter? Of wat moet ik anders aanpassen?

The path has become part of a fenced private terrain with no gates, so has become non-existent. Perhaps 'highway=no' is more appropriate?