Can I practice in Basque?

Yes, and with full support: Basque is available as a practice language in all modes. Course texts, series, the marathon, and benchmarks are generated in Basque. The application interface is also translated.

How to enable it

In Settings → Practice languages, check Euskara. You can combine it with Spanish or another language, up to three at a time: the exercises will alternate.

About the keyboard: Basque is written using the standard Spanish keyboard, so there is nothing to configure.

If you also want the entire application in Basque, change it in Settings → Interface language.