When I install any crank on a BB, I never base the "correctness" of the install on how far down the taper it goes, but more on how tight I am torquing the bolt. I also never expect the spindle end to be flush to the bottom of the bolt well on the crank arm. All my installs always have a gap between the end of the spindle and the top of the tapered square hole, sometimes a bit more than what you show. You should have stopped tightening the bolt when you were feeling a lot of resistance already as it could only result in a snapped or stripped bolt. If the bolt was already so tight, you should trust that the crank will not go anywhere/move on the spindle anymore.
I'd remove what's left of the bolt and put on a new one but not try to tighten it too much again to try and get the spindle deeper into the crank. I just hope you did not overtighten it so much with the first bolt that cracks might start to develop at the tapered hole.
BTW, I also never use torque wrenches and do all my bolt tightening by feel which had worked for me for many years.

Chombi