If you have World Machine, couldn't you just import your Gaea tiles to wm, and then export to unreal specs from there?
Also, did you check the video someone posted in THIS thread of yours? It's for unreal engine 5, so there may be something in there that helps. I'm reposting the video here, in case anyone else comes across this thread.
Instead of reposting the same questions repeatedly, I'd suggest you post a comment here itself. Easier to follow a single question for prospective commenters. That said, good luck! Let us know if the wm workaround works.