Hi Stephen,
I find this fascinating. A long time ago this precise issue briefly came to my attention, but did not think too much about it as I had many others to think of. I agree with you on the need to create hedges that better match our expectations of natural language, and this is something I would be fond of discussing what the best approach would be to incorporate it into the next version of fuzzylite.
What you mention using a hierarchy is interesting, but is not generic enough. This would make sense if we have a negative-to-positive set of terms like lo-med-hi, but would not apply for sets expressed as fast-faster-fastest, for example. I am inclined towards leaving this option to be set manually, creating positive and negative hedges. An idea would be “very-” and “very+”, where “very-“=x^2 and “very+”=\sqrt{x}.
Lastly, have in mind that hedges were originally conceived to affect the antecedent of the rule, which they do unambiguously (yet not as intuitively). The possibility of adding a hedge to the consequent is thanks to the design of fuzzylite. You can create any number of hedges and seamlessly incorporate them into fuzzylite by registering them in the HedgeFactory.