I name my bolt circle parameters and use the "Text" to put in "ON A _ DIA B.C." after the hole note with the corresponding parameter where the _ is.
If the drawing uses fractions the parameter is still in decimal.
If I had regular leader text I could "Edit unit attributes" but this is not available for hole notes - any place you can put a parameter should have this option.
You could make a way to have a bolt circle dimension available within the hole note that would reflect the hole note formatting to solve my immediate problem but I still think that any place you can put a parameter should have the "Edit unit attributes" option.