The period of church reforms of the middle of the XVII century is one of the important stages in the development of the Church Slavonic language, in which the norm stabilizes as a result of editing and printing of liturgical texts, and the Russian literary language in the new conditions of correlation with the Church Slavonic language and expansion of its own borders. Textual approach allows to determine the main directions of changes in the systems of these languages. Genetically correlated reflexes of the Slavonic diphthongic combinations are the diagnostic signs of the East Slavic and South Slavic languages. Multiple-editions of the First petition of Archpriest Avvakum chosen for study. The analysis shows that the full-voice / non-full-voice vocabulary recorded in the message is represented mainly by South Slavic correlates, with different preferences for equivalents of correlative pairs of the -глад-/-голод-. The implementation of heterogeneous reflexes * dj as a whole corresponds to the Old Russian manuscript tradition and suggests that the strengthening of the South Slavic жд is not the result of the so-called second South Slavic influence period, but is determined by editing of the church literature of the XVII century. Against a wide background of the South Slavic designation of the suffixes of real participles of the present tense, the realization of reflexes *tj is genetically diverse, which causes the emergence of transplants of the type тружающiися. Editorial editing of the First petition in the XVIII and XIX centuries was directed towards strengthening the realization of the South Slavic-derived reflexes. Each of the analyzed groups creates a complex pattern of implementation of genetically correlated reflexes, which leads to a heterogeneous genetic background of the text, including due to the content of the First petition, close to The Life of the Archpriest Avvakum by Himself.