We added the EU Event Calendar some time ago after it got requested by players to make EU events more visible.
Right now, pretty much all events on there are mirrored on the US calendar as well. Which makes sense as EU evenings are also EST afternoons so they are relevant for both time zones.
To make it less work for event organizers and people in other time zones than EU & US I am considering to remove the EU calendar and merge them together again.
But since this has been a request, I'd like to see some discussion about it first. Maybe I am missing something.