The main difficulty is that some (all?) of the rotations don't work. To explain that let us examine the hip.

In the image above the pretzel figure on the left has your BVH applied. The hip rotations are:-
Bend -59
Side-side 43
Twist -71

I copied these hip rotations to the figure on the right.

Now whichever way you transpose those rotations I do not think there is a combination that works.

Sometimes you'll find that the rotations have been transposed, the BVH has the up-down axis as Z whereas Poser uses Y. Then its relatively easy to edit the BVH file to transpose the values. However here I do not see any combination of reordering that will work.

I am willing to be wrong but to my best understanding that is what I see.