I'm sorta flying by the seat of my pants beyond what i said there ... but,
because it depends on your NwN2 system ( mods, mods-unknown, etc )
I suspect that at some point you've installed a mod for large-screens, which tend to increase font sizes. But unless the entire Gui is then changed to account, the above can happen.
so Here's how I work things ...
copy 'fontfamily.xml' from
<install>\UI\default
to
<documents>\ui\custom
Note that if there is a fontfamly.xml in a .Hak or \Override, those would take priority over these.
now you can tweak that file all you want, if you need specific pointers, pls ask specific questions

Or .. i could just post my
fontfamily and see if you like it. Chuck it in <documents>\...\Override and take it for a test drive.
That'd mean you don't have to edit nx2_market.xml .. but all this really depends on whether you have a secretive fontfamily OR nx2_market .. somewhere.
How do I edit the xml files?
with a text editor