AFAIK, the interpolators don't use marvin's timing code, which is not really good. I don't know if there are similar classes which do a similar job taking that into account. In any case, that would be real easy to implement it.
Please to a fresh SVN checkout, since there was a misspelling of GroupRotator which was named GroupRotater.
See org.xith3d.test.animation.RotatableGroupTest for an example.
But as an easy fix you should use the following for all you startIncreasing() calls.
pAI1e.startIncreasing( this.getGameTime() );
You'll certainly call pAI1e.getValue( gameTime );. And this won't work, if you don't start with the current gameTime.