It’d be very nice to be able to map numeric fields (ie. energy, danceability, etc) to the “Rating” field in Engine DJ. I’ve done some experimentation on this myself - I wrote a quick and dirty Python script to read the “Energy” from the IDv3 tag and write it as the “Rating” in the Engine database.
Internally, the engine rating is just an integer from 0-100, with each grouping of 20 being a new star (ie. 0 stars is 0-19, 1 star is 20-39, etc). It seems that Engine doesn’t complain about having a rating of say 24 points, but I just rounded things off to increments of 20s (but this may mean they sort differently). It would be great to be able to do this in Lexicon directly!