Can you please try out the latest MRIcroGL pre-release (v1.2.20210816). When you choose the "Multi-Planar A+C+S+R" from the "Disply" menu, you will see all four views show a cross-hair and all interactively move to the location of a mouse click:
  https://github.com/rordenlab/MRIcroGL/releases/tag/v1.2.20210816
The formula is described here
  https://github.com/rordenlab/MRIcroGL/tree/master/DepthPicking