Hmm... further progress: I have taken the supposed factory values from this post (
https://groups.google.com/d/msg/colorhug-users/NB7tdh4ojIw/HBgS1G6svz4J), I have tried to put them in a ccmx file on the style of
http://www.hughski.com/downloads/colorhug2/ccmx/unity.ccmx (changing the identy matrix values to the ones taken from the post), and the very weird thing is, the ColorHug loads only some of the values (off-diagonal), and not the ones on the diagonal (using colorhug-cmd set-calibration-ccmx). I managed to get all the values using colorhug-cmd set-calibration and then the single values, but the ColorHug doesn't like the resulting calibration, deselecting it at each restart and refusing to take most measurements with it (take-readings works, take-readings-xyz fails).
Now I'm even more confused... any help please?