@db0255 ...
I'm not familiar with the CrossFire software; I've always used Crossword Compiler to construct puzzles, but the principle behind grid-filling software is probably the same: that the constructor pre-assigns a number -- usually from 1 to 99 -- to each word in the word list. Then, when the software is invoked to fill a grid, it will first try the words with the highest ranks (or word score) and work it's way down to lower ranks until the first successful fill is achieved.
Perhaps someone familiar with CrossFire might chime in to elaborate on those other scores you mention; they don't appear to be universal.
-Joe