When i created this thread, i didn't know, where this 10 limit comes from.
Later i searched the servo drives docs and even found the limit mentioned there...
Will try to move some settings to SDO.
But its still annoying, because homing alone has more than 10 PDO parameters (eg speed, torque limit, time limits, etc). Many of them are somewhat just "nice to have".
But it seems, if i want to use them, i would need to switch ethercat-conf.xml (multiple times) during a linuxcnc program run. If that is even possible.
However in the near term i will go the simple route and stay within the 10 limit.