Validation of fields that are part of a composite field doesn't work as single fields. For example:

• for field 'longitude0' I created a regexp validator - work as expected (error message on red background)
• for field 'longitude' which is part of a composite field 'location' I created same regexp validator - there is no error message and invalid values disappear when focus is gone. E.g. typing 'asd' and pressing tab - field becomes empty.

Screen after saving form and configuration in attachments.