Hello scaalmap,
You made a mistake here:
https://www.openstreetmap.org/node/12849007594#map=23/48.48177420/-2.46515410&layers=V
by tagging natural=wetland=marsh.
First you tagged a node with that tag instead of an area;
Sencond you should have tagged it with:
natural=wetland
wetland=marsh

Marc Zoutendijk  
OpenStreetMap Foundation  
Data Working Group  
