Tween Curves, crazy results, can't set the start point

Do I understand the tool right?

Just want an even transition, doesn’t work with lots of curves when in center.

Thank you

the startpoint of the circle is not in the right position when you draw it on the cplane grid.

It has to be on the diagonal of the rectangle:

so just rotate the circle accordingly
(I don’t think there is an option to set startpoint loctaion, it is just for flipping the crv)