Don't install Smite to an NTFS partition, or at least force the compdata to be on an ext4 partition. The main issue I had with Smite is EasyAntiCheat and prereqs. Eventually I only got Smite working with Proton 4.2-9. To resolve the EAC issue you need to install and get Paladins working and copy the right files from Paladins' EAC to Smite. Prereqs can be installed using protontricks.

Step by step:

• Set Proton to version 4.2-9
• Install both Smite and Paladins to an ext4 partition
• Run Smite (it should close due to EAC or prereqs) and Paladins (use this Steam post on Paladins if Paladins doesn't start)
• Use this Steam post on Smite instead of Paladins (so replace the Paladins id with Smite's id)
• From the Steam/steamapps/common/Paladins/Binaries/EasyAntiCheat/ folder copy everything except for the Certificates and Launcher folder to the Steam/steamapps/common/SMITE/Binaries/EasyAntiCheat/ folder
• Now copy both EasyAntiCheat dll files in the EasyAntiCheat folder to Steam/steamapps/common/SMITE/Binaries/Win32/EasyAntiCheat/ and Steam/steamapps/common/SMITE/Binaries/Win64/EasyAntiCheat/

This was the only way I got it to work in the end.