More interactive curve fillet tool?

[Rhino_Bulgaria (Bobi)]

I found a case that seem to look quite interesting (no tangency on either end of the right-hand side curve):

Fillet curves 1.3dm (136.6 KB)

However, I do get a tangent radius on the upper end when I use the following script (sadly, it does not support a “flip” function):
FilletCrvTest.py (13.0 KB)
FilletCurves.rhp (21.5 KB)