Loach eggs don't normally stick in plants and you never see them actually spawning. So removing plants with eggs doesn't work. And plenty of loaches lay eggs in the substrate.
As with Corydoras, if the adults are well fed they do not appear to eat their eggs or young.
I had 20 young fish in a 4ftx2ftx2ft community tank with big barbs, rainbowfish and some other stuff living in it. The tank had a home made undergravel filter that had 2 uplifts, one on each side of the tank. The tank had about 4 inches of natural brown gravel and lots of plants. The loaches use to spend part of the day under the undergravel filter plates, and the rest of the time in the tank swimming around everywhere. They worked out they could go down the uplift tubes and live under the filter. Every day at feeding time you would see a train of loaches come swimming up and out of the filter uplift tubes. It was hilarious.
As to where they actually bred in the tank, I have no idea. All I know is I put 20 fish in the tank and a couple of years later there were about 50 of them consisting of 20 adults and 30 young that were about 1 inch long.
A friend of mine had a similar experience. I gave him 12 loaches when I got my 20 (got the entire batch at a discount price from a shop). He put them in a 6ft x 14inch wide x 18inch high tank with an undergravel filter and a few plants and some driftwood. He had lots of small tetras and catfish in the tank. His loaches lived under the driftwood. Within 12 months his fish were 6-8inches long (mine only reach 4-5inches, females being bigger than males), and after a couple of years he started getting 1 inch loaches appear in the tank.