"They travel abroad more often than we."
Translation:De reser oftare utomlands än vi.
Yes it sounds unusual, but it is not wrong. The French dicussion forums are full of this debate (it isn't really a proper debate since both are right). Additionally, it's good to teach this equivalent in the Swedish (than I, than we, than he, than she etc.) because in the Swedish it's more common among native speakers "Han kan inte så mycket svenska som jag... / Hon är bättre på att laga mat än jag..." https://www.merriam-webster.com/words-at-play/than-what-follows-it-and-why