I have to unfortunately report the same problem with the schedule after reaching any European competition. Like @JakobDoyon wrote above, we only get between 1-2 days of rest between games. If we're lucky we get 3 days.
Apparently it's solvable in real life so it would be very nice to see it solved in game or at least get an explanation as to why it can't be solved.
I only play the Swedish league and have done so for each and every FM game. This problem has persisted since the beginning.