I’m not sure exactly what you mean by “libertarian” free will, but I’ll give my understanding. Buddhism is definitely not deterministic. It accepts the effects that social conditioning, genes, etc have on us, but insists that that conditioning influences rather than determines how we act.

At the same time Buddhism doesn’t have a naive view of free will. We can’t just decide to be happy, for example, and expect our emotions to suddenly comply with our desires. We can’t “control” ourselves totally. Just as genes and social conditioning influence rather than determine how we act, so too our will only influences, but can’t determine, how we act. Another way of putting this is to say that our will is only partly free.

At any given moment we have a limited power to influence what we do, but the important thing is to act on that limited power. In doing so we find that we have greater power to exercise our will — our will becomes more free and we find that it becomes easier to be what we want to be and do what we want to do.

Enlightenment could be described, perhaps, as point where we have the ultimate amount of free will available to us, resulting in a great degree of freedom from suffering.

I hope this helps. Remember that I’m not a philosopher but just a practitioner, so please don’t take this as an authoritative statement on Buddhist doctrine. This is just my understanding of how things work.

All the best,
Bodhipaksa