I've been using Degrafa library for some time in a Flex 4.6 project and it's apparently running fine with this version. The only issue I've encountered was with some of the Degrafa's components when upgrading to AIR 3.9 (you can read the post here but it was for the bezier-curve component anyway), but nothing wrong before that.
If not done already, you should try upgrading the library to its latest patch. Their website is down but you can still find latest downloads here.
About your question "What library can I use instead?", tell us which components are you interesting in. If you're only using one or two from Degrafa, it could be found somewhere else easily.