The trouble is with pan-national trends is you have to draw with incredibly broad strokes, otherwise every sentence you say will be burried under asterisks. Yes, you can daw up a General narrative comprising, among other things, the SNP, the South China Sea, Flanders, Make America Great Again, Artur Mas, Crimea, Tsipras, Panzergirl, Shinzo Abe, the Pan-Green coalition, Gerry Adams, Kurdistan, the Islamic Calpihate and how they were each prompted by certain contexts of contemporary times; but it probably won't be very useful. Even if you limit it to the various nationalists that have sprouted in the Eurozone the best you can say is "Brussels screwed up as per usual in regards to the euro and the refugee crisis, and caused an upsurge in nationalist sentiment rooting from each nation's unique tradition and character'. And even then I would be wary of drawing pan-national trends even as broad as that. It's not like upswings in nationalism and anti-immigration sentiment has been completely foreign until the last half-decade.
The last sentence merely indicates that the trend towards nationalism is older than a half-decade.
Again, either the simultaneous rise of such movements is coincidental, or it is not. If it is not coincidental, arguments that attempt to create some meta-explanation "aren't very useful" are irrelevant because the situation demands a meta-explanation however difficult formulating such an explanation is and no matter how little power such a theory has. [The trees mays be of different species, but, that doesn't mean they don't constitute a forest. A forest grows because the climatic conditions favor a forest over grasslands, or such, etc. Sure, the last explanation is rather simplistic, while an explanation of why any particular forest has hardwoods versus evergreens, or visa versa, is more complex. But, the existence of the forest necessitates an explanation as to why there is a forest.]
Suppose, some force had the ability to impose their will in the formation of a EU-type union of India, Pakistan, Bangladesh, Nepal, and Bhutan. How would such a union turn out? Meta-theories would make predictions. Since French culture is simply different than the cultures of India, Pakistan, etc., explanations for the rise of the FN would have no predictive power. I, for one, would see such a union suffering from massive internal frictions leading to nationalistic movement within the member states.
