I have a 3-band parametric equalizer in my SVS subwoofer. I do a couple of frequency sweeps in REW, specify the 3 filters I have available and then REW computes the settings for the subwoofer equalizer. It works really well!
If/when the parametric equalizer feature is released, it should be possible to use the same procedure for the WiiM. Don’t know how many room problems the parametric equalizer in the WiiM will be able to fix.