Your comments

Yep! Fixed a long time ago, closing :)

Sure, I can give this an extra look.

Do you have an example of a node tree that is a common case that should look cleaner?

Ticked this one off a bit prematurely - it has definitely been fixed now in 1.23 :)

SM2.0 has a bunch of weird limitations all over the place. The SM2.0 feature is experimental for that reason, so I'll leave this as-in, given that you got it to work :)

This has been fixed in 1.22, which is releasing soon

Looks like you're missing the node data files. Try doing a clean reinstall of SF like this:
http://acegikmo.com/shaderforge/faq/?Q=erroronnewversion#erroronnewversion