Well the game considers that I used them as the dialogue now has the option of about how the characters feel about their new powers, and I now have the illithid powers icon just above and to the left of the mini map. It now shows a "1" next to that icon and when clicking on it, it shows the first power has been unlocked. This icon was not previously their prior to receiving Minthara as a companion as I loaded a save before minthara being save.
But yes, Mint is the most bugged character that needs lots of fixing.
