No, checked all the permissions, and as I said - simply moving the data to a case-insensitive FS instantly fixes the issue. Besides - strace shows explicitly that the game tries to access files under a wrong name.
Can you check if you can access the same file in the home directory under different cased names? E.g. create a file "TEST.EXT" and see if you can open it under name "TEST.EXT" and just as well as "TEST.ext"?

[eugene@eugene-home ~]$ cd ~/.local/share/Baldur\'s\ Gate\ -\ Enhanced\ Edition/save/000000000-Auto-Save
[eugene@eugene-home 000000000-Auto-Save]$ touch TEST.ext
[eugene@eugene-home 000000000-Auto-Save]$ ls
BALDUR.SAV BALDUR.gam PORTRT1.bmp PORTRT3.bmp TEST.ext
BALDUR.bmp PORTRT0.bmp PORTRT2.bmp PORTRT4.bmp
[eugene@eugene-home 000000000-Auto-Save]$ ls TEST.EXT
ls: cannot access 'TEST.EXT': No such file or directory
[eugene@eugene-home 000000000-Auto-Save]$ touch TEST.EXT
[eugene@eugene-home 000000000-Auto-Save]$ ls
BALDUR.SAV BALDUR.gam PORTRT1.bmp PORTRT3.bmp TEST.EXT
BALDUR.bmp PORTRT0.bmp PORTRT2.bmp PORTRT4.bmp TEST.ext

What is your ~/.local/ FS type? For now BGEE has problem with large xfs partitions (probably this will be fixed in the next version of game, 64 bits are needed).