Hi everyone,
We are working on a project that is trying to clean up and update river data globally. In short, we look to fix errors like disconnected waterways, overlapping water areas or waterways, correcting broken multipolygons, fixing mistagged features, removing duplicate objects and importantly, also moving older river tags (waterway=riverbank) to the newer more numerous version natural=water + water=river.
More details are written up here:
https://wiki.openstreetmap.org/wiki/WikiProject_Waterways/River_modernization
Let me know if there are any possible issues with running the modernization in Switzerland.
Cheers,
Martin