Sorry, todevastate, I can't really help (I'm a PC man), but is it not possible to "cut & paste" the required section into a text editor and save that ?

Other news:
On looking more closely at the keyframes resulting from an imported BVH file, I realised that the abdomen is not used at all; all the "action" takes place in the chest area. (This may be what "Chest2" is all about - the (input) "Chest" might be the abdomen, and "Chest2" the chest - but I'm only guessing and probably wrong).

However, with all that action in the chest, some overly severe bending can occur at the join of the chest and the abdomen, especially in the more extreme poses.

So I set to again with Python and devised another little script that averages the "Bend",  "Twist" and "Side-Side" values between the chest and the abdomen (ie, 1/2 Bend in chest, 1/2 in abdomen and same for the other parms).

The result seems to be somewhat smoother and more natural to me.

If anyone else wants to try the script, I'll post it here (it's not very long - just a bit longer than the "Flat-foot V4" script above)

Alternatively, IM me and we can arrange for an exchange of e-mails..

Cheers,
Diolma