Tales of Xillia [BLES01815]

Has the gamma issue been fixed (clearly seen in the Namco Bandai intro screen)?

No, it hasn't been fixed yet, as far as i know anyway. You need to manually enable libsysutil.sprx in the firmware libraries to fix it but doing so crashes the emulator. On old versions (like one of 0.0.4) it's possible to go through the intro screens but you can't go ingame anyway.
P.S Btw i'm just passing the info from other guys in the rpcs3 community. So apologies if what i saild ends up being incorrect.

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DLC the game is freezing when i install that.

You can use only a handful of DLC without issues. So if you install too many of them the emulator crashes.