Hello JP,
The problem with this layer is that the data is not stored as area on the zoom level it can be requested (see picture below, the dropped pin is the coordinate of the request from last email) but as a mesh of points, one each 100mx100m
I think I've found something that could work, but it's not straightforward :
1. Grab the coordinates you have and round them up to the closest 100s, in your case : 539384.0,151774.06 => 539400,151800 (there is a data point every 100m in each direction)
2. Transform this LV03 coordinates into LV95 by adding 2'xxx'xxx and 1'yyy'yyy to the coordinates : 539400,151800 => 2539400,1151800 (usually it would be better to calculate the equivalent with a projection tool, but here you just want the closest LV95 100s coordinates from your LV03 coordinates)
4. Sort/filter the results to find the one with the most recent survey year (they are not sorted according to that)
So a bit of coordinates transformation, and sorting, but it should work and you should have your information :-)
(You might want to change the lang of the identify request with the &lang= param)
Hope it helps,
Pascal