I've extracted the .pak file in "romfs\HeroGame\Content\Paks" and transfered the Content of it into romfs itself.
The result looks like this now:
Then I copied the "GUI" Folder inside "romfs\HeroGame\Content\L10N\en-US" to "romfs\HeroGame\Content" which replaced all japanese textures with the english ones.
After that, I've rebuilt it to an working NSP (non public method with SDK)
but it should also work with LayeredFS!
Cons: The game is much bigger than 3GB now (7GB if you delete the L10N folder, which isn't needed by the game to run currently, 10GB with the LI0N folder).
The Reason for this is because pak-files are compressed. The compression is gone as soon as you extract the content
It contains these languages
View attachment 140937