Sorry about your floor. Water intrusion usually isn't considered a warranty issue. It's usually considered "user maintenance/user responsibility"...
That said, with your 2023 trailer, you are still under the structural 3 year warranty. That more or less, puts you between a rock and a hard place if you're living in the trailer and can't take it to a dealership. Why is this so? Some, maybe many issues that happen on the assembly line are considered a "manufacturer's responsibility" and Keystone will repair those issues using the warranty. Without a dealership being involved to report the condition and their "expected cause assessment" then Keystone won't even consider any repair. It ALL has to start with the dealership.... Even then, depending on what the dealer finds and what he documents, that report will, for the most part, determine how Keystone considers a warranty repair...
All that considered, the "hard place" comes into play when you start ripping things apart to repair them yourself. As soon as you tear out the first structural component, you void the warranty and neither Keystone nor the dealership will work to "fix what you took apart".... (call it the "rock")
So, if you are concerned that it's a "manufacturing issue" then you either have to follow the Keystone rules for warranty reporting and hope the report is in your favor or you just do the repair with the knowledge that no matter the cause, you are footing the entire cost for any repairs. (call this the "hard place")...
Now as for "owner repairs, there are a few threads on this forum that discuss a slide floor repair. A couple of them are fairly detailed and photos of the process.... While it "might be possible" to repair the entire slide floor with the slide installed in the trailer, the most effective and best way to repair it is to remove the slide (not a task for the average trailer owner) and to lay the slide on its side so the entire structure is accessible to do the work.
Have you even discussed this problem with the dealer's service MANAGER and the dealership OWNER/MANAGER ??? I'd skip the service writer who is instructed on how to proceed with NORMAL work orders, not with SPECIALIZED problems that have "manager/owner involvement"... If you get them involved, you might get some specialized consideration as long as they understand your situation and the trailer's condition. It may be worthwhile to talk to management at the dealership....