Also the High Judge (RR) seems good in concept but brings it down by a HALF POINT per skill, meaning even a skilled one is almost useless
I used High Judge when I am in a very big rush at 1650 at the end of Holy wars. Take multiple wars and don't care about the WE. It is usually a disaster afterwards. 5-6 star High Judge pull out of the mess earlier. Besides AFAIK RR cuts your economy. So it might has some economical advantage.
The advisors I personally have not ever used:
Spymaster, Colonial Governor, Alderman, Colonel, Banker, Lord Proprietor, Quartermaster, Military Engineer, and the Inquisitor.
I've used all of the others, most with some regularity. I can see a possible use for all of the above.
Colonel has some use against the horde. When you want to cut through Timurids faster to reach India. Another use if you want to outrun a neighbor in colonizing waiting for each other who reach 1000 first and then place the colonist.