I may be wrong, but I think that the vertical keystone can be improved by a side to side adjustment of the 45 degree mirror. I would not assume that the 45 degree rails are perfect.
The focus looks fairly uniform, I suspect that moving the CRT foreward or backward will sharpen it quite a bit... perhaps put a dab of lubricant on each of the 3 "fingers" that move the CRT mount so the focus action is smooth.
jr