Hi @karnabal,
Thank you so much for getting in touch, we do appreciate your time.
The ‘User’ string is available within the PO file for most languages, however, it may be marked as a ‘fuzzy’ translation which means the PO file would need to be opened, the string would need to be marked as complete/not-fuzzy, followed by resaving the PO file to generate a new MO file.
Both these files would then need to be uploaded back to the plugin directory via FTP or cPanel in most cases.
When using a language management plugin like WPML or LocoTranslate, these steps can often be avoided. These plugins often include their own functionality to remove the need for altering the PO files directly.
I hope this helps?