Так называемый «старославянский язык» является искусственно созданным языком, обслуживающим население обширных территорий восточной Европы

The so-called "Old Slavic language" is an artificially created language, serving the population of large areas of eastern Europe.

Yes or No ???

No. It's dialect of extincted Slavs living arroun  Thesaloniki in IX century. It was enriched by influences from Byzantine Greek, mostly in way of making new words, but it almost eclusively used Slavic roots. :) Also it had some local influences, but it is not aritificiaily created, it's codified dialect improved for liturgical and literal use. Church Slavonic is newer version created amogn Eastern Slavs, it has more Eastern Slavic influence, and it is today in use by Slavic Orthodox and Byzantine Chatolic Churches.