If you know all the required data for the C50 v5, you can create a new dataentry via https://openwrt.org/meta/create_new_dataentry_page (need to be logged in to the wiki to be able to create a new dataentry).
The datatables on the devicepage will automatically show C50 v5 once the dataentry has been created.
I created a new data entry page, but made a mistake when prompted to enter 'version' number. I originally inputted '5' instead of 'v5'. It has created a page with URL ending in '5#' instead of 'v5':