with smaller goldies, yes. I have successfully kept and bred them (although the latter was unintentional! )

No I don't think it's a good combination. They need higher temprature and the substrate needs to be very fine and soft because of their mouth. They need dark spaces and lost of woods and organic stuff. All things not very good for goldfish.

they do prefer warmer water, although im sure adapetd to my cooler water, and they prefer higher PH(which I have)

they do need hiding places, mine had a treasure chest they always stayed underneath. These did not bury themselves....my other loaches bury themselves all the time, but I never saw the Khulis do it.

is that loach in the photo pregnant?

yea its full of eggs, i remember reading from the site it came from and this guy managed to (unintetionally) breed quite a few!