The Leonardo has a different CPU architecture. That means different timers with different properties that I would have to wrap.
So far, Arduino microcontrollers use three main architectures 'groups'. Arduino Mega and ADK are of the AVR mega 1280/1281/2560/2561 group, which are all identical except for the amount of memory they hold. The Leonardo uses ATmega32u4. And pretty much everything else uses 88/168/328 variants.
I have an Uno and a Mega, which means I was able to build and test for every architecture except the Leonardo. If there is enough interest in this project, I would be willing to try to get it working on the Leonardo. But I have no reliable way too test it in real life to make sure it works.