I'd like to set my standard font (which I use everywhere else in Directory Opus) in the renaming panel as well, but the preferences won't let me. There are only monospaced fonts to select from. Why? How can I enable all fonts to be selectable in this area?
That is the font for the rename macro builder, not the whole rename panel.
The macro builder edits all filenames at once, so the characters have to line up and the font has to be monospaced.
You can turn off the macro builder using the checkbox near the bottom of the rename dialog if you don't want to use it.