I use Linux Mint and have installed Ardour 6.9 localized to German from the repositories.
Is there a possibility to change the language to English?
Remark: under Bearbeiten/Globale Einstellungen/Übersetzungen I deactivated “Benutze Übersetzungen” but it did not change the language in Ardour (of course after restarting Ardour).
6.9 is rather old at this point, and there may have been issues disabling translations. Please use a newer version - there is a free demo available at Download Ardour | Ardour Community that can be installed in parallel with your distro version.