https://bugs.winehq.org/show_bug.cgi?id=43464
--- Comment #10 from Peteris Krisjanis pecisk@gmail.com --- Dmitry,
I just realized that Win32 version of launcher had interesting similar issue - .NET launcher passed arguments to EDClient.exe and client responded 'Please launch game from launcher'. It tried to pass parameters from launcher, it seems they might be borked there. Win64 responds differently but that might be just way it is checked.
When launching EDClient.exe from launcher, you can check process list and see it is launched with parameters. Those might be culpit.