So, just a response to myself. I was able to get this working by install Ephinea through Lutris using the "+" at the top-left of the application, then installing the game as a Windows game with the EXE installer. Once the game installed, I clicked on the up arrow beside the Wine logo when...
I was able to run the launcher inside of Lutris on my Steam Deck but after installing the online.exe patch from the game, the launcher won't launch any more. Has this happened to anyone else?