Not really... it's not a common request, and I think it is still best to change it from the theme itself...
Or you can remove the font declarations altogether, from the theme, and then add them in via the Custom HTML form...
I've been trying to get a few tweaks made on the fileownership plugin I started last week along with another of mine that is dependent upon its data and I've run into a wall.
As posted last week, it was listening for the fileUpload hook. The problem with that is you end up putting data in the database for a file that might be decoupled from the message ( deleted, etc. ) and then you end up with file references cluttering the database.
Today I moved it to the topicPost/topicReply filter. This was a little better in that I knew I was dealing with the final state of the attached files for an initial post/reply ( fails utterly with edits... ) message but the file has not been moved/cloned from "/tmp" to the nodebb filesystem making it difficult to get any metadata ( size, etc ) from the file.
I tried moving it to the topicPost/topicReply actions, which occur later - but it was rather inconsistent.
This has me thinking a few things.
One - I'm doing a lot of this wrong headed and I need to completely rethink storage to account for editing messages.
Two - I need a hook that fires after the file has been moved from the tmp filesystem into the nodebb space. Does one exist?