Hi,
Please go to BO > Localization > Translations, export the translations to a .gzip file from the old site, then import it to your new site.
Best regards.
Hi,
You can unzip the file to your local, there is such a FR-fr or US-en folder, upload it to /themes/transformer/translations folder, then remove all files from /var/cache/prod/translations folder.
Best regards.