@Lampiao
Byzantines were irregularilly called Romans by Latins (I don't think that labelling Foulcher de Chartres or Etienne de Blois isn't really accurate: most crusade chroniches* were achieved in the first years of the XIIth century, furthermore), in a political sense rather than ethnic tough : either as inhabitants of the Romania under the emperor, either eastern or orthodox christian outside Romania (probably under the influence of rûm used by Arabs to call melkites, sometimes other oriental Christians as well)
Romania, isn't a loanword, but rather a word inherited from late Latin to medieval Latin and romance languages.
Now, how this word was used by Latins certainly refletcs the use of other derivated words as Rhomania, or rûm, but it's really hard to consider that a basic ethnonym of the late Empire was totally forgotten and that Latin use of Romania is only taken from medieval Greek.
Now, this use of "Roman" always was paralleled since the Xth century, from the use of "Greek" especially (but not only, political claims and boasts were pretty much important too) as Roman was used for naming western regions (Italian Romania, for exemple), populations (Aquitains, and more important the people of the city of Rome and such the pope**) and of course the language (
Lenga Romana for Old Occitan)
*To be distinguished from choniclers of the Latin states, tough
** Which is what Romanorum refers to, for what matter the imperial claims in western Europe