A friend sent me his ATH-M50xBT2 for a test. I attached a measurement compensated for my target which shows some stronger channel-imbalance and a similar response to what RTings had measured.
The headphones comes with an own app which provides a parametric 5-band EQ. Unfortunately the filters are quite limited as you cannot set precise frequency or Q-values and only +/-6dB gains are available.

Nevertheless I tried to create a rough EQ to bring the sound closer to my target as well as a variant with a more Harman like bass, which should be the more correct setting actually. It’s far from perfect but definitely way nicer sounding than with the default setting.