Under 'Λήψη -> Δοκιμαστικές' (Download -> Test) Contents starts with Δοκιμαστικές Εκδόσεις LibreOffice 3.5.2 RC2 (2012-03-29) Outdated! But below the OS / Language selector correct versions are offered.
Page fixed, https://el.libreoffice.org/download/pre-releases/ Thanks Rainer!