Thanks to information of Serge Poncet I learned that on the mountain-top of Querroig four submarkers of bm597 will be engraved (if the proposal will be approved by the “Commission mixte Franco-Espagnole”). Why? Apparently there were groundworks scheduled around the ruins of the former castle which could change the watershed and therefore the borderline.
In 2014 a team of officials made a reconnaissance of the terrain and marked the four rocks where the bordercrosses could be engraved when the project will be approved. I don’t know when that will be. In their report they list the coordinates which makes locating them on Google Earth easy.

The rocks in question were provisory marked with yellow paint crosses and spots. Like this one (bm597c):

Update 2017 or 2018: according to Serge Poncet, the project has been abandoned due to the estimated high costs.