You are right, I forgot about the rsvp pro plugin :S.
1. Taking a look at the plugin translation there were some "duplicated" strings that made it to not show the trasnlation properly. I have solved it and I think that the screen shot that you posted should be correctly translated now (obviously you have to download and install again the package from our downloads area).
2. There still remains some untranslated strings in the plugin, I'll contact Lars and I hope he can assist us soon.
Thank you very much for your corrections and your patience.
¿Sabías que tenemos soporte en español para los miembros del Club de JEvents? ¡ÚNETE AHORA!