This aspect was discussed before here http://forum2.dev.xiligroup.com/topic.php?id=145. XL to try to solve this aspect proposes a fieldset in backend named Translation domains settings
For experts in multilingual CMS: Check to modify domains switching.
with two check boxes:
Switch all domains excepted default WP
default…
Calendar function as date or time format are worked in WP by his global $wp_locale which is depending from the localisation of the backend. So to live separate back (admin) and front (theme) in multilingual context, can be a nightmare for plugins…
I never test calendar… but will do inform in one or two days