Sentence:  Proficient in Church Slavonic (necessary for the psalomshchik), fluent and literate in both <WSD>Unalaskan</WSD> Aleut and in Russian, conversant also in English, and an Aleut-Russian himself, he wrote this lengthy letter, and others published in the same collection, in the <WSD>Unalaskan</WSD> Aleut language. 
Meaning of the word marked with <WSD> tags:  The eastern dialect of Inuktitut.