@ Dušan

It looks like a poetry

Things I notice that will never been written in east Slavic languages are врх, црне, кршу, дршћ, мршаве, ишту, трне,

It’s impossible to have 3 consoнants in a row in east Slavic languages. Such words are separated by vowels. If we have 3 consonants, even two consonants in a word on many occasions, then they are likely to be loan-words from Old Church Slavonic (Old Bulgarian) or Polish.

Glas, grad, Vladimir are old Church Slavonic loans. In eastern Slavic languages these term would be Golos (Golas), Gorod (Gorad), Volodimir.

PS Vladimir Ulyanov and Vladimir Putin are Russian names. But still Vladimir is a loan in Russian from southern Slavic languages.