MEIOU & Taxes is allowed to have a Facebook page. Other EU IV mods are not allowed to have one.
IIRC @Castellon answered to me that mods are allowed to have social media,webpages, etc, as long as those don't behave like a forum (i.e. discussions with the unregistered users, distributions of downloads, etc).
Edit: here: https://forum.paradoxplaza.com/forum/index.php?posts/18246744/
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