That’s never been confirmed by Blizzard just something a certain people peddled.
They can disable quests. The en_GB client is essentially the en_US client, unfortunately.
There are also data sharing laws between the USA and European Union so that’s not an issue like some used to bring up.
WoW can’t be region transferred because back in 2004 it was never built like that. All other later games have been built with that in mind. Blizzard could of course build that service but would they spend all that time just for ‘one person every week’ to use it. No.
The Wolpertinger quest isn’t available in europe, it didn’t pass the PEGI 12 rating in some countries. Blizzard removed the quest on european servers, instead europeans must buy the pet for 200 tokens. Unless it was changed recently.
And since it’s a new Warcraft account you still have to pay monthly separate to your current EU Warcraft account. Like you would ANY new Warcraft account.