The new form-field class localized_text text solves the goals of for providing a formfield interface to message keys in a loca fashion rather than altering the behavior of all form field and of all property interfaces.
This class can be used to provide an interface for specifying internationalized text strings saved in message keys via input from a form. When editing the content provided via the input field is saved together with an item-specific message keys in the message key tables via lang::util::convert_to_i18n.
This formfield class is especially useful for xowiki items which have no language-prefix (e.g. folders or links). In other cases it is probably still a better idea to create same named pages with different language prefixes.