After installing F18 (TC3) in Spanish the First Boot is run and these screens are localized, but these translations don't match with the last PO in Transifex (https://fedora.transifex.com/projects/p/fedora/language/es/?project=2124 from June 2012).
Benjamin, do you still see this problem in the GA DVD? (the release one)
Benjamin, It looks like you misunderstood that screen.