AFAIK, the hatch closing speed should be no different whether pushing the button on the hatch, drivers kick panel or keyfob. I slowed down the speed of mine so it doesn't slam as hard and it now soft closes with all 3 buttons.
Here's the thread I started which includes the values I used, YMMV.
https://x3.xbimmers.com/forums/showthread.php?t=1884001