What file permissions? How should I have done this? I just made a fresh install. And what tests have you made? Launching a rom outside the standard path with or without symlink?
Of your roms. Where do you have stored them and what filesystem did you use? Probably an external hard drive and you use it on Windows based systems too? Otherwise google for fstab and mount the partition to the game folder.
The game has multi languages how else could I have boot it in german when I chose full boot.
I just booted the bios.. and it is set to german. I also tested a different game but same result. Full boot -> german, fast boot -> english.
Sorry if I understand you wrong but PCSX2 isnt included in LE too. You added it. And the Langs folder is usually stored in the pcsx2 config folder together with those ini files etc. If pcsx2 can read those ini files why shouldnt that work with the Langs folder too?
I tried Baldur’s Gate: Dark Alliance 2, GoW2, GT4, MGS3 and I could change the language for all of them. Gran Turismo 4 for example created a user profile and the language was saved too. All config files for PCSX2 are readable & writeable so if you can change the language settings for games it will work. The user interface of PCSX2 has nothing to do with the games you actually run. It's just the frontend like in Citra or Dolphin.
Some games need the full boot otherwise there wouldn't exist the --fullboot option. So editing es_systems.cfg to
<command>/usr/bin/pcsx2.start --fullboot %ROM%</command> should do the trick.