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I found message "does not appear to be valid" isn't translatable. Other messages aren't translatable also. They need to added in translatewiki.net
Thanks for reporting this. Would it be possible to report this in an OpenStreetMap tracker? That would increase chances if this actually being addressed. http://wiki.openstreetmap.org/wiki/Bugs describes the procedure, I think.
Can you explain where you saw this message? Maybe it is one of the standard rails form validation messages? If so then it would need to be translated as part of the rails-i18n project as it comes directly from rails.