Redirect after reservation confirmation

I’m using the plugin in conjuction with WPML. The default language of the site is Dutch, the secondary language is English (at /en/). When making a reservation on the English reservations page the plugin shows the Dutch thank you page instead of the English one (so /reservations/ instead of /en/reservations/). Anyone know why this is happening?

The page I need help with: [log in to see the link]