try to delete all 0804 mui, then rebuild it. You don't need to replace by 0409 mui, because it's set by default interface for a WWE rom. 0804 mui is to create a CHS interface.
Try it, and report.
Edit: forgot one thing, you will have to work with initflashfiles.dat (in CHS rom it's in Chinese soo you can't use it in WWE rom), it will create your device's structure, like : Folder windows, in Windows there are Startup, start menu... quite difficult, but to make it easy the only thing you need is the new sys (with new build, you can get it from CHS or CHT rom, after delete all 0804.mui, or any languages) and OEM from jigg's Rom.
I hope you could understand what I mean.