Here are the official titles of Catholic European kings in the 13th century.
Lithuania 1261:
Mindowe, Dei gratia rex Littowie
Hungary and Croatia 1270:
Stephanus dei gracia Hungarie, Dalmacie, Croacie, Rame, Seruie, Gallicie, Lodomerie, Cumanie Bulgarieque rex
Denmark and the Wends 1251:
Abel dej gracia Danorum Slauorumque rex
dux Jucie
The Franks (France) 1246:
Ludovicus, Dei gratia Francie rex
The Swedes and the Goths 1276:
Magnus dei gracia sweuorum gotorumque rex
Bohemia 1291:
Nos Wencezlaus, dei gratia rex Bohemie,
dux Cracouie et Sandomerie,
marchioque Morauie
England 1261:
Henricus, dei gracia Rex Anglie
Dominus Hibernie et
Dux Aquitannie
The Scots 1240:
Alexander dei gracia Rex Scottorum
Sicily Naples 1289:
Karolus secundus, Dei gracia rex Jerusalem Cicilie, ducatus Apulie & principatus Capue
princeps Achaye,
andegavie provincie et forcalquerii comes
the other Sicily 1282:
Petrus dei gracia Aragonum et Sicilie Rex
Latin Empire of Constantinople 1205:
Balduinus, eadem [Dei] gracia fidelissimus in Christo imperator, a Deo coronatus, Romanorum moderator et semper augustus,
Flandrie et Hainoie comes
Jerusalem 1258:
Conradus dei gratia Ierusalem et Sicilie rex,
dux Swevie
Antioch 1219:
ego Raymundus Rupini dei gracia princeps Antiochenus,
Raymundi principis fili
Cyprus 1252:
Nos Henricus Dei gratia rex Cypri
Norway 1264:
Magnus dei gratia rex Norwagie
Poland 1295:
nos Premislius secundus, Dei gracia rex Polonie et
dux Pomoranie
Portugal 1259:
ego Alfonsus dei gratia Rex Portugalie
Aragon, etc. 1231:
nos Jacobus, Dei gracia, rex Aragonum et regni Majoricarum,
comes Barchinonensis et
dominus Montispessulani
Castile, etc. 1249:
ferdinandus Dei gratia, Rex Castelle et Toleti et Legionis et Gallicie et Seuille et Corduue et Murcie et Jaheni
Navarre 1223:
nos Sancius, Dei gratia rex Nauarre
Emperor 1226:
Fridericus secundus divina favente clementia Romanorum imperator semper augustus,
Jerusalem et Sicilie rex
http://eurulers.altervista.org/index.html1
What language are these title from 13th century documents written in? Almos t all are in Latin. They show that many documents in Catholic European countries were written in Latin.