"...Is there a way to tie star common name display to magnitude?"

Unfortunately, no. You can turn them on (show all common names
all the time), off (don't show any of them at any time), or auto
(show all of them, but only at narrower fields of view).

_However_... I just thought of a way to evade all these problems,
and wrote up the following file (about 18 KBytes):

http://www.projectpluto.com/common2.tdf

Download this and put it in your Guide directory, and you'll see
common star names appear. To evade duplicates, you should go
into Star Display and shut off the "Common Star Names" option there.

The advantage is that common star names will then be shown only
as a user-added dataset. You can turn them off, on, set a limiting
magnitude, and determine the fields of view at which they are shown.
You can also select the color used.

-- Bill