TarasD
Just checked today and the administrative boundary lines that were only visible in the ID editor are now gone. I don't know what that was all about but "Fleuve St-Laurent" still appears over land (at zoom 13 and 14).

I used JOSM to examine how Fleuve St-Laurent is defined. It is easily understood east of Lac St-Louis. However, how the river is defined within the lake itself is unclear to me. Hopefully someone else has the time and expertise to resolve this issue.