If you need more help you will have to post logs and maybe someone will see whats wrong, however proton doesnt really give good logs, so you might be better off switching to wine-ge
Ive never played elden ring outside of steam. It works perfectly there. For reference tho: proton isnt exactly meant to be used outside of steam so you can run into issues
I think this wont work because of Anti-cheat. I think you can try to run a different EXE if there is any and enable EAC runtime on Heroic. Although I am not sure Elden ring use those runtimes