Are there any patterns for loanwords phonetics in Russian which are specific for a source language?

Question

В (древне)русском языке есть (был) набор специфических фонем. В языках, из которых осуществлялись заимствования, тоже был набор специфических фонем. Вопрос: могли ли одни и те же звуки (древне)русского языка быть обусловлены разными фонемами? Например, звук я в предположительно заимствованном слове "варяг": может ли он объясняться в т.ч. и уральским e/ä?

(The Old) Russian has (had) its specific set of phonemes. The languages from which the words were borrowed also had sets of phonemes specific for them. The question is, could same phonemes in (Old) Russian be results of different phonemes in source languages? E.g. я in the supposedly loaned варяг: can it be a transformation of Uralic e/ä?

Answer 1

According to Vasmer and Vinogradov, варяг is loaned from Old Norse *varingr, "a trusted one", remotely related to Russian вера.

At the time, Slavic had nasalized vowels ѧ and ѫ (preserved in modern Polish as ę and ą), the former sounding similar enough to -in- to substitute it in loanwords.

Later Old Slavic nasalized vowels turned into a and у in Russian so *варѧгъ became modern варяг.

There are several other Germanic loanwords following the same model: князь < *кънѧзь < *kuningaz (PG), витязь < *витѧзь < *vikingr (ON), чадо < *чѧдо < *kind (disputed) etc.

On the other hand, Finnish, which had also loaned words kuningas and ruhtinas from Proto-Germanic, preserved the combination -in-.

This fact, as well as the fact that the loss of nasalized vowels was a common Slavic process not limited to areas populated by Uralic-speaking people, argues against Uralic influence on the loss of the nasalized vowels and hence я in Russian варяг.