First of all, I'm gone ask you this:
Are you requesting a face that has this feature?
If yes then sorry to say it, but you are using a wrong category.
Under "feature requests" facer creators post request for Facer staff (like adding a new option for us to use inside a watchface that we want to create).
If no, then I'm sorry I understood it that way.
If you want a new face made that would utilize a feature that you are not sure exists yet then sent me a private message - I consider myself a specialist on creating new math mechanics.
If you are interested in using both types of temperature at the same time on a face that you are creating, then try reading this quick tutorial I created some time ago: http://community.facer.io/t/showing-temperature-in-both-c-and-f-at-the-same-time/5236