BC,
The tubular end of the transition track is dimensioned to be identical to 'O' Gauge Track. Thus the tubular end is no different than either end of a standard O Gauge straight track section.
So, to me your statement then becomes "I have tried to connect O Gauge track to O-27 and it was practically impossible to get it to mate up with the O-27." Am I right with my interpretation?
Given that O27 was introduced about 75 years ago this turns out to be one of the oldest questions asked about mating track in the postwar era, and it comes up VERY often on this forum. The answer is: No it's not impossible. In fact in most cases it's only mildly difficult, with a little persuasion and, of course, a shim to raise the O27 up to reach the holes/pins on the end of the O Gauge section.
Perhaps there's some issue with your O27? Is is old (vintage), or new? Clean or dirty? Lionel or Marx?
Let us know what you find. It shouldn't be that hard especially if its newer, relatively clean, and made by Lionel.
Mike
