There is not really a date on Pitforge. The game does not revolve around a specific timezone.
However when announcing things (I.e when raiding will be enabled), the administration usually gives out a timezone. Most of the time it’s Eastern Standard Timezone, which is the timezone in which most American players can relate to.
I would recommend just learning the time differences between common American time zones and common European timezones so you can easily do the math in your head. Or, which I even use sometimes, I just Google “timezone converter” and it allows me to enter the time in one timezone to get the time in another.
I think that would be easier than adding a Minecraft plugin.