Time format
We are not using any framework for time formatting. We're using the browser.
Traccar Manager Android app I was referring to is not a browser. I have just tried FireFox for Android and to show the time on Traccar web interface it does follow the time format setting regardless of what system language is. On the contrary, Traccar Manager app on the same Android phone ignores the time format setting and displays time in a format dependent the system language setting. That is not very intuitive
Traccar Manager uses the browser engine (WebView).
You are correct it is a webview issue. Top firefox and bottom is chrome (splitscreen screenshot):
Not sure about most because the only other places I use time/date extensively enough to matter to the point I would have to change between AM vs PM and MM/DD/YYYY vs DD/MM/YYYY are calendar and messaging. Both gmail and Google Calendar have that option in the web settings. As for android app pardon a small criticism of otherwise great app the framework you are using is broken. For example, the calendar app I use aCalendar+ and the mail app FairMail both follow the time format setting I have in the screenshot above and not the system language setting.