I want to rename "Fax" to "Mobile" on the backend (Create New Order page). I assumed this could be achieved by updating my
en_GB.csv file in my child theme.
Assembling the preceding pt_BR.csv files across all modules and the current theme results in a Portuguese translation of the entire application area (storefront or the Admin). - Magento Docs
However, this does not appear to have any affect. Is this label actually translatable? I prefer not override a file for something so trivial.
Note: My translation file works fine for everything else and cache is currently disabled. So I know it's nothing like that.