You can hope it is not a seaping weld, and honesly it does not sound like you do.
Few things-
Try this...
1. It may sound crazy but check how tight your transom plugs are. My buddy swore he had a leak and all it turned out to be was that the nut on the back of the plug runner was loose and the rubber wasn't compressing enough. Not trying to sound silly, but the first thing a electrical technician is taught is to make sure the device is plugged in (LOL). Didn't leak when we filled it, but during a day of fishing water was seaping through the drain plug. We tightened it, and the problem was solved. If you haven't checked this, it is one possibility.
2. Another test that has helped us in the past for isolating the area is.... With the plugs in and tight, put the boat in the water (on the trailer) with just the back 3' of the boat into the water (so the bottom of the boat is wet). Leave it sit for 4-5 min and see if you are getting any water in the hull. If you don't you can be fairly sure the damage is not isolated to the back 3' of the boat. If the ramp is shallow enough, (and not busy) you can back the boat in roughly a foot at a time to give you a smaller area to focus on. Also with the boat on the trailer it will have more down weight (pressure) which can only help.
3A. I am not familiar with the livewell system on a Legend, but most are bottom drained through plumbing. I saw a boat once that tourny friend had and the boat came in once with an inch or so of water on the bottom of the boat and he was devistated. His new 42K bass boat was leaking. Here the plumbing line in that livewell drain was cracked and leaved water into the bottom of the boat.
3B. Another friend of mine had a Tracker Targa with 2 livewells and a bait well. The front livewell "overfill" drain was clogged and when he filled the tank and had it on the fill timer, it would fill just a fraction too high and with the boat in the water they do not sit 100% level. The water was spilling out under the deck where the livewell and the bottom edge of the front deck met. Crazy, but after a full day in a Walleye tourny in NY, we had som 20-30 gallons of water in the bottom of the boat! Took us days to figure that one out!
Not sure if any of this will help. But hopefully something here does.