Sorry man but that is ridiculous. People did not speak more than one language unless they lived in a border area. The #1 thing that was drilled into nobles was how to wield a weapon, they started learning that before they turned 8 years old. Then came riding, running, etiquette and religion. For religion you often learned Latin but not even all kings could speak that.
There's a funny anecdote about how one of the Otto emperors (a smart one) met the French king in Italy, and rather than speaking French (which Otto knew as well as a bunch of other languages) he spoke to him in Latin. Because the French king knew neither Latin nor any other languages, and Otto wanted to intimidate the man before they would go over to state business.
I'd be surprised if the princes of Sweden learned anything besides a few words of Latin, Sweden was a backwater that was barely Christian in 1066. I guess a prince could go abroad to serve as a mercenary or Varangian guardsman but what use would he possibly have of foreign languages back home? No Swede ruled any foreign lands.
Sorry man, but
this is ridiculous.
You can take an example of the Grand Duchy of Lithuania in the 14th-15th centuries (is this enough Eastern European and "backward yesterday's pagan" country for you?). Both Jogaila (later King of Poland) and Vytautas were fluent in Lithuanian, Ruthenian, Polish and Latin. There are documented evidence about the Council of Luck in 1429 that the lords who visited it (except mentioned Jogaila and Vytautas also emperor Sigismund, Danish king Erik of Pomerania, Grand Master of the Livonian Order, almost all the electors of Holy Roman Empire and many other lords form Eastern and Central Europe) spoke to each other
without any translators in Latin and German. Even more: when Vytautas wished to address his relative Jogaila in secret talks he used their native Lithuanian as kind of "crypto language" because none could understand it except them.
Even earlier there are lot of evidences that during the 14th century the delegations form the Teutons and the Livonians found that the "barbarian" pagan Lithuanian ducal court was fluent in both their German and Latin languages. You can check for more details in nice article about such direct contacts and their linguistic aspect: Rowell, S.C.
A pagan's word: Lithuanian diplomatic procedure 1200-1385, Journal of Medieval History, vol. 18 (1992), namely pages 145-159.
Several Lithuanian princes such as Kestutis' son Butautas (Christian name "Heinrich") or the latter's son Vaidutis (Johann), or Lithuanian noble Survila (Thomas) were baptised in 1365 and in 1366 settled in the court of emperor Charles IV in Prague. Butautas-Heinrich was granted a formal imperial title of "herzog von Litauen" and the lands in Bohemia. Check: Rowell, S.C.
Unexpected Contacts: Lithuanians at Western Courts, c. 1316-c. 1400 // The English Historical Review, vol. 111, No. 442 (Jun., 1996), pp. 557-577.
Later Butautas travelled in the retinue of the emperor to Rome, mentioned many times in important ceremonial events that took place in 1369-1377. His nobleman Survila made a carrier in the Teutonic Order and in 1370 received lands in Trinkheim (Brandenburg), travelled a lot in Europe, visiting even London. Are you seriously thinking that they were communicating with the emperors, dukes, clergy by gestures or something?
And really please be a bit less categorical when we are discussing history.