Mental Fabrication and Empathy Is there a difference, in terms of mental fabrication, between creativity and imagination (which seem to rely on imagining what's not there) and empathy and mentalizing (which understand how someone's mind/mental affinities are)? Are empathy and mentalizing more 'mindful' and produce less mental fabrication?
As your question implies, creativity, imagination, empathy and mentalizing all have their root in our ability to think abstractly (among other things). 

However, I’m not sure that the psychological constructs of empathy and mentalizing corresponds directly to buddhist theoretical concepts, but they can surely be interpreted as components of the brahmaviharas virtues. They are wholesome, since they ameliorate aversion/dosa. 

I don’t know, but I suspect that one can’t consider brahmaviharas an actual decrease in mental formations (if one could ever count/measure formations at all), as much as a replacement of unwholesome formations into wholesome ones (according to the principle of  right effort).