I believe the answer is that you cannot import the latest FC library into Pega and expect it to work. But I could be wrong too. It is my understanding that every Pega version ships with a default version of the FC library so we are pretty much restricted to the use of features supported by that specific version of FC for the corresponding Pega release in question. I am going to request one of the community moderators to confirm this for you. Thank you.
Sunny is correct, you can't manually update the version of FusionCharts thats shipped with Pega. FusionCharts will change some of their API's or options each release, which sometimes requires us to make changes to use the latest version. When 8.2 is released, it'll include an upgrade to 3.13 but there isn't a pega release in between that has an upgrade.