I'll be updating this post as a find more. I'm not searching every nook and cranny, just the common areas listed in the OP.
HK-51 - Imperial Side - Tatooine
He makes comments on the Mos Ila Siltshift Cantina and the Junkyard
A friend has told me his HK-51 made comments on the Geonosisans on the Republic side (quoted below), but he didn't tell me where, i'll ask him when he comes back online.
Places i've tried:
Dorumand Kaas exiting the spaceport and entering the Sith Sanctum he made no comments.
Exiting the Spaceport on Tatooine he said nothing
Balmorra nothing at the common areas listed
On the Republic side, for me he said nothing at the Coruscant Space Port or the Senate tower.
taris- Imperial - Toxic Lake Settlement
Leaving the platform where the shuttle to the orbital station is he says
Imperial - Approaching the Endar Spire
Imperial Quesh - Arriving
Empire - Voss - Shrine of Healing