Thanks for posting this!
The 'favspell' entry is interesting, this might confirm my early hunch that each caster seemed to get a little fixated on their favourite spell... an impression I discarded as silly anthropomorphic imaging
so maybe I was wrong on that.
I'd guess the -1, -2, -3 values are special disqualifications. I'd guess -1 is out of range to start with... and then we can discard that hypothesis almost immediately I think... I never use fire flies so I'm guessing, but doesn't it have at least as much range as flying shards? So it's something else... the really wierd thing is that it seems like it settled on mossbody(?) as the best choice, then cast summon earth power anyway... geez... gonna take some time to figure out how to parse this thing properly. Anyone already figured it out by chance? Might really clarify a lot...