Not as cool a visualization, but https://www.swissgrid.ch/swissgrid/de/home/reliability/wam.html https://www.swissgrid.ch/swissgrid/de/home/reliability/wam.h...

Not as cool a visualization, but https://www.swissgrid.ch/swissgrid/de/home/reliability/wam.html https://www.swissgrid.ch/swissgrid/de/home/reliability/wam.h... shows the frequencies and phase differences (in degrees) between a few measuring stations around Europe. The phase difference between Switzerland and Spain is now some 50°, which is actually much larger than I would imagine these differences becoming.