Question: What was the nationality of the student of Jan Baudouin de Courtenay and member of the Kazan School? 

Context paragraphs:
Hugh de Courtenay, 1st/9th Earl of Devon: Hugh de Courtenay, 1st/9th Earl of Devon (14 September 1276 – 23 December 1340) was the son of Sir Hugh de Courtenay (died 1292), feudal baron of Okehampton in Devon, by his wife Eleanor le Despenser (died 1328), sister of Hugh le Despenser, 1st Earl of Winchester.  Forty-one years after the death of his cousin, Isabel de Forz, "suo jure" 8th Countess of Devon (1237–1293) (née de Redvers, eldest daughter of Baldwin de Redvers, 6th Earl of Devon (1217-1245)), letters patent were granted by King Edward III, dated 22 February 1335, declaring him Earl of Devon, and stating that he 'should assume such title and style as his ancestors, Earls of Devon, had wont to do'.  This thus made him 1st Earl of Devon, if the letters patent are deemed to have created a new peerage, otherwise 9th Earl of Devon if it is deemed a restitution of the old dignity of the de Redvers family and he is deemed to have succeeded the "suo jure" 8th Countess.  Authorities differ in their opinions and thus alternative ordinal numbers exist for this Courtenay earldom.

Portrait of Baudouin de Lannoy: Portrait of Baudouin de Lannoy is a small oil-on panel portrait by the Early Netherlandish painter Jan van Eyck, completed c. 1435.  It shows Baldwin of Lannoy, a contemporary Flemish statesman and ambassador for Philip the Good at the court of Henry V of England.  From surviving documents it is known that the work was commissioned to mark his entry into the order "Baudouin de Lanno".  He is in a formal pose, holding a wooden stick in his right hand, and a gold ring on his little finger.  Van Eyck's surviving early portraits typically show the sitter holding an emblem of his profession and class.

Kazimieras Jaunius: Kazimieras Jaunius (1848–1908) was a Lithuanian priest and linguist.  He started his studies in linguistics in the end of 19th century in Kaunas.  While Jaunius did not publish much, his major achievements include research on the similarity of Lithuanian to other languages and the systematization of research of Lithuanian dialects.  He collaborated with Jan Niecisław Baudouin de Courtenay and Jonas Basanavičius.

Matilda I, Countess of Nevers: Matilda I, Countess of Nevers or Mathilde de Courtenay, or Mahaut de Courtenay, (1188–1257), was a noble of Nevers, Auxerre and Tonnerre.  She was the only daughter of Peter II of Courtenay and of Agnes of Nevers, born from the Capetian House of Courtenay, she was married to Hervé IV of Donzy and then to Guigues IV of Forez.

Kazan school: Kazan School was an influential group of linguists in Kazan.  The linguistic circle included the Polish linguist Jan Baudouin de Courtenay and his student Nikolai Trubetzkoy.

Hugh Courtenay (died 1425): Sir Hugh I Courtenay (after 1358 – 5 or 6 March 1425), of Boconnoc in Cornwall and of Haccombe in Devon, was Sheriff of Devon for 1418/19 and was thrice elected knight of the shire for Devon in 1395, 1397 and 1421.  He was a grandson of Hugh de Courtenay, 2nd/10th Earl of Devon (1303–1377), was the younger brother of Edward de Courtenay, 3rd/11th Earl of Devon (1357–1419), "The Blind Earl", and was the grandfather of Edward Courtenay, 1st Earl of Devon (d.1509), KG, created Earl of Devon in 1485 by King Henry VII.  He was the link between the senior line of the Courtenay Earls of Devon made extinct following the Battle of Tewkesbury in 1471 (his elder brother's line) and the post-Wars of the Roses creation of a new Earldom for his grandson made in 1485 by King Henry VII.

Nikolai Trubetzkoy: Prince Nikolai Sergeyevich Trubetzkoy (also Troubetskoy; Russian: Никола́й Серге́евич Трубецко́й; Moscow, April 16, 1890 – Vienna, June 25, 1938) was a Russian linguist and historian whose teachings formed a nucleus of the Prague School of structural linguistics.  He is widely considered to be the founder of morphophonology.  He was also associated with the Russian Eurasianists.

Jan Baudouin de Courtenay: Jan Niecisław Ignacy Baudouin de Courtenay (13 March 1845 – 3 November 1929) was a Polish linguist and Slavist, best known for his theory of the phoneme and phonetic alternations.

Baldwin II, Latin Emperor: Baldwin II, also known as Baldwin of Courtenay (French: "Baudouin de Courtenay" ) (late 1217 – October 1273), was the last monarch of the Latin Empire ruling from Constantinople.

Cezaria Jędrzejewiczowa: Cezaria Jędrzejewiczowa or, Cezaria Anna Baudouin de Courtenay Ehrenkreutz-Jędrzejewiczowa (1885 – 1967) was a Polish scientist, art historian and anthropologist.  She was one of the pioneers of ethnology in Poland and one of the first scientists to adopt phenomenology in studies on the folk culture.

Supporting paragraphs: Kazan school Nikolai Trubetzkoy
Answer: Russian