I think it's very democratic when e.g. turks can vote in e.g. germany. I also do not mind when foreign politicians come to other countries for political rallies. That's, however their business and they have to pay it out of their own pockets.
I mean think about it, when every single country suddenly wants to go on rallies in foreign countries is the local tax payer rly supposed to sponsor all of that and on top of that their oppositions, too, maybe?
The real question EU member states have to ask themselves is if they support a foreign government or not? I think kim jong un probably wouldn't get the go ahead from the EU if he wanted to visit us to teach us some real politics