The rear rack Bosch battery holder is really badly designed; at least, on our 2016 Motus, but I think the mount is the same on most Bosch rack batteries. It is much worse than our (Chinese designed?) frame battery holder which just lets the battery slip into the correct place every time.
My main quibble is that it is very easy to get it almost correctly located but not quite. Connection is still made, still locked at the front, but it has lots of movement at the back and is (as you describe) very difficult to get out. I'm sure its damaging the connectors too.
My current way to get it located it to put in on the rack so it is a couple of inches from being closed, then let it rest, and then push it into place from the back (neither lifting the back up nor pushing it down). Putting it in in a single movement is very prone to error; too high at the back, too low at the back.
If the issue isn't with getting it placed exactly try a little Vaseline or a tiny smear of light grease on the runners.