Located within the Proton prefix path: $HOME/.steam/steam/steamapps/compatdata/1259970/pfx/drive_c/ (followed by the Windows path above) . Distinction: Edit Files vs. Database Files
.../SiderAddons/livecpk/[ModName]/common/etc/pesdb/Player.bin . Player.bin Pes 2021 Location
C:\Program Files (x86)\Steam\steamapps\common\eFootball PES 2021\data\ Located within the Proton prefix path: $HOME/