This is because of the language settings on your phone. Normally if your phone language is not supported by RaceChrono, it will default to English. On iOS there is a “Preferred language order” that will override this behaviour: If your first preferred language is not supported by RaceChrono, the second language on that list will be selected, and so on. Make sure you have only the languages you want your apps to appear on that list. You can find the setting from Settings > General > Language & Region.

The languages currently (17th January 2019) supported by RaceChrono are English, Chinese (Simplified), French, German, Italian, Japanese, Portuguese, Portuguese (Brazil) and Spanish.