thanks for the feedback.
Unfortunately, I'm not able to reproduce the issue - setting the app language to Spanish still shows 24 hours format. Maybe it's an issue with a specific courier? If so, please send the tracking ID and courier name in question to firstname.lastname@example.org so I can take a proper look at it.
Please also note that you can manually force a time format at Configuración -> Diseño -> Formato de hora. Setting it to "Formato 12h" showed AM/PM properly for me.