https://bugs.winehq.org/show_bug.cgi?id=39471
--- Comment #22 from Andrew Eikum aeikum@codeweavers.com --- If you want to try to diagnose this yourself, that would be wonderful! I don't have a lot of spare time to work on this right now.
We actually have a set of Windows VMs for developers to test on, so you don't have to maintain an installation yourself: https://testbot.winehq.org/
What we want to do is test whether Windows can convert WMA audio with acmStreamOpen. What you'd need to do is dump the complete WAVEFORMATEX structure that the game is passing to acmStreamOpen (we're missing the extradata past WAVEFORMATEX in your log). Then in <dlls/msacm32/tests/msacm.c>, call that function in the same way. You can then build a crosstest, upload it to the testbot, and see how Windows behaves.
In Wine, we return 512 (ACMERR_NOTPOSSIBLE) since Wine can't convert WMA. If Windows returns 0 (success), then Wine should support this conversion. If Windows also returns an error, then the problem lies someplace else.