The Orthodox tradition rejected this 'Three Tongues' Heresy', sticking to the initial choice of the Church. These principles had been held in the wonderful work of St. Cyril and Methodius, which forever laid such an indelible imprint upon the whole internal order of the Russian language. It is strange, however, to think of the ironic fact that many are wishing now to immortalise Old Church Slavonic by the help of that very theory, which once had served the enemies of the Solun's brothers' work. It is strange that that very Slavonic liturgical language, created to bring the Sacred nearer to the consciousness of our ancestors, is today helping to keep distance between that very Sacred and the consciousness of their descendants. The experience offered here is only an experience, liable to the judgement of the sensible critics, not to mention the judgement of the Church.
Boldness is a great responsibility.
The Lectionary is part of the Holy Tradition of the Church. Its antiquity is witnessed by it being the same across all 20 independent Orthodox Churches. The actual rubrics as to how to put the readings together can get quite complex, although the basic principle is rather simple. You check the menaion section for today's date and see if there is a reading specifically for today's saint. Then, you check for a reading in the paschalion based on the week and day after Pentecost.