ok so far it seems the probes quantity are not balanced while ur doing mission u actually get roughly around the same amount pinpointer probes and multispectral but u need to use the pinpointed probes more often to determine the location of the aliens so u always run out of em while still having tons of multispectral.
most of the times the special items u receive from this aliens are actually resource items like gold carbon etc. its not really that special for someone who already has a mining facility already doing that.
lastly most of my encounters with the unknown aliens their FP are always on level or lower that my tail ships which means if i have a lead of ard 100 Bil FP and my last ship has a FP of 10 Bil FP the unknown alien would usually be below 10 Bil FP and i feel thats a bit too low.