Very unlikely. First, I can't see your post having much actual financial impact on the site, so the cost to sue you in the U.S. would likely exceed what the site might win even if defamation could be proven. Second, if the only connection to the U.S. that is involved is that Google cloud hosts the site, a U.S. court is almost certainly not going to have jurisdiction to hear the claim. Note that while Google is headquartered in the U.S. it operates cloud servers all over the world. It is likely that the site is actually hosted on a server in Europe rather than the U.S. Finally, even if it was possible and the admin got a judgment against you in the U.S., that judgment is only good to get assets you have in the U.S. Domesticating the judgment to another country where you have other assets might be possible if that country either is party to the international treaty that provides a process for it or has its own internal law that allows for it and even then it is likely not a cheap process to use.