Hi,

the following example works for author-year, but funny enough for
numeric the Kyrillic and Roman versions of the author name are scrambled
(Kyrillic doesn't transmit on usenet, check
https://tex.stackexchange.com/questions/645615/how-to-cite-a-few-
russian-sources-in-an-english-document for the correct bibtex-entries).

How can I correct that?

\begin{filecontents}[force]{test.bib}
@ARTICLE{Smi-39,
AUTHOR = {{\foreignlanguage{russian}{???????, ?.}} [Smirnov,
N.]},
sortname = {Smirnov, N.},
shortauthor = {Smirnov},
TITLE = {{\foreignlanguage{russian}{?? ??????????
???????????? ?????? ?????????????}} [On deviation of the empirical
distribution curve]},
sorttitle = {On deviation of the empirical distribution curve},
YEAR = {1939},
JOURNAL = {{\foreignlanguage{russian}{???. ???????}} [Math.
Collect.]},
volume = {6(48)},
number = {1},
pages = {3-26},
langid = {russian},
url =
{http://www.mathnet.ru/links/9c480a97757553ea3504fc444cde8430/sm5810.pdf
},
}

@ARTICLE{Kol-33,
AUTHOR = {Kolmogorov, A.},
TITLE = {Sulla Determinazione Empirica di una Legge di
Distribuzione [On the empirical determination of a distribution law]},
YEAR = {1933},
JOURNAL = {Giorn. Ist. Ital. Attuar.},
volume = {4},
number = {1},
pages = {83-91},
}

\end{filecontents}

% -*- TeX:UK -*-
% !TEX encoding = UTF-8 Unicode
% !TEX TS-program = xelatex
% !TEX spellcheck = en_GB
% !BIB program = biber
\NeedsTeXFormat{LaTeX2e}
\documentclass[british]{scrartcl}

\usepackage{kpfonts-otf}
\usepackage[main=british,russian]{babel}%foreign language support
%\usepackage
[backend=biber,bibencoding=UTF8,sorting=none,style=authoryear]
{biblatex}%bibliography
\usepackage[backend=biber,bibencoding=UTF8,sorting=none,style=numeric-
comp]{biblatex}%bibliography
\usepackage{csquotes}%context-sensitive quotes, required for biblatex
%\usepackage{fontspec}% font selecting commands
%\usepackage[T1,T2A]{fontenc}% For Cyrillic fonts with pdflatex.

\babelfont[russian]{rm}{Liberation Serif}
\babelfont[russian]{sf}{Liberation Sans}
\babelfont[russian]{tt}{Liberation Mono}

\addbibresource{test.bib}

\title{Test}
\author{Tester }
\date{\today}

\begin{document}

\maketitle

The quick brown fox\parencite{Kol-33,Smi-39} jumps over the lazy dog.

\printbibliography[heading=bibliography]

\end{document}