Hi Soertano,
I agree with your observations, You should also post this on the
Issue tracker :
http://code.google.com/p/google-mapmaker/
Current workaround for this is to avoid ending roads where rivers/
railways end. Any road intersection that snaps with the intersection
of a river or railway section will make the intersecting sections of
the Road/River/Railway un-editable and give the message "Failed to
edit or delete the requested Road".
Regards,
Map Maker Guide.