Water boy will be named after drink. So I decree!
But very true, and I hope Nomura doesn't do that with everyone in Dark Road. It already kinda wore out its welcome. lol
And Xehanort knowing them would be why Xemnas knows the two are connected with the "ancient Keyblade legacy." And then we'll complain about Master Xehanort not having any interaction or even acknowledging them all throughout KH3.
They still have a chance to appear in UX, but at this point it's a safer bet they'll be in DR.
The worlds having different flows of time because of their restoring process can also be an excuse for why Luxord's still young. He stayed in Verum Rex for one reason or another while it was still in early recovery and time didn't flow for him again until decades later.