Of course I could be wrong, but I was under the impression that the low point drains drained the fresh water tank and water lines. In my Eagle 266 RKS travel trailer, there are two in front of the axels (controlled by valves inside the bathroom vanity - one for hot and one for cold), and two behind the axels (controlled by water jug-style turn valves underneath the trailer). I believe the water you're getting from the low point drains is water left in your lines after you've disconnected from your "city water" connection. It's suppose to do that to clear the lines of water in preparation for winterizing. You can also open them and turn on the water pump to facilitate the FW tank draining/sanitizing process.
With 65 gal. grey water storage, you likely do have two grey water tanks: one forward for the kitchen sink, and one aft for the bathroom sink and shower. The black water tank, of course, only serves the toilet. With 48 gal. fresh water capacity, you may have only one fresh water tank; and one pair of low point drains. Someone with a 23.5 FW may be able to confirm whether you have one pair or two.
The grey and black water dump valves are always guillotine valves with "T" shaped handles, which are normally grey and black to designate their respective tank colors. Look for one black/two grey. They should be clearly marked on the side of your trailer.
Sounds to me like everything is operating as it should!