I have a possible solution for the endurance Datacron, located in the Library ruins at coordinates -726, -257 (same area where you find one of the lore objects for the exiled knight), there is a switch with an orange rune on it, the same orange rune you'll find in the hidden personal phase at coordinates 1378, -376 over in the Ancient ruins. Now I'm no rocket scientist, but I think you'll need 5 people to all click the switches either at the same time or in the color order presented for something to happen..... my guess it unlocks that Jedi Holocron in the Library for you to take and pop into the Holocron Receptacle. I've only found that one switch and it was completely by accident, I can only imaging the other 4 are scattered around Ossus so good luck