The clan milestone engram which is supposed to grant a powerful engram was the only one that was broken and according to Bungie is now fixed. It should drop at higher than current power level. The other clan engrams, earned for the clan by fellow clan members were not broken and only drop at the legendary levels appropriate to your character’s level. If your power level is under the softcap of 340 it can drop at a higher power level. If your character is above 340 it will drop at or +1 of your current power level, though far more likely at your current power level. These clan engrams are meant more to get you weapons you have not seen than to upgrade your level.