ValidationError messages for NumberTextFields with minimum/maximum are always English

Although my Form's Locale is, e.g., de_DE, the error message generated from AbstractRangeValidator#validate(IValidatable) is always English.
My German custom message for resource key "RangeValidator.range" in the Page's resource bundle gets ignored too - the default custom message from the resource bundle is used instead.

Reason might be that Component#getLocale() invoked from Localizer#getStringIgnoreSettings(String, Component, IModel, Locale, String, String) always returns NumberTextField#HTML5_LOCALE (fix for WICKET-3591).

Pls. see attached quickstart.

I'm a Wicket newbie, so could very well be that I'm missing something.