>> A related glitch in Carrara 6 is the use of "constraints", to restrict the bending of joints.   Terai Yuki 2, for example, as loaded, can't bend her elbows more than ninety degrees.   You can free the constraint, so that she can bend her arms more realistically, but the restrictive default seems totally pointless.<<

The "Use Constraints" feature in Carrara is the same as the "Use Limits" feature in Poser. If you put "Use Limits" on in Poser, you'll find the same limitations in TY2. So part of the problem is that TY2's joint limits themselves might be too restrictive.

Now ... the solution in Carrara. There's a toggle for "Use Constraints" in the upper part of the document window. Turn it on or off before you load your scene and you should be good to go.