The template you've shown uses a sans serif font without Cyrillic characters (TeXGyre Heros). Therefore you won't be able to put sentences in Russian as is. But you can change the fonts. I've tried to add the following lines to the preamble of cv.tex
:
\newfontfamily\bodyfont{Fira Sans}
\newfontfamily\thinfont[]{Fira Sans Light}
\newfontfamily\headingfont[]{Fira Sans Bold}
\defaultfontfeatures{Mapping=tex-text}
\setmainfont
[Mapping=tex-text, Color=textcolor]
{Fira Sans}
\setmathfont{Fira Sans}
\usepackage[russian,english]{babel}
They switch the document font to Fira Sans
(it's a nice free font family with wide range of weights and with Cyrillic support). After that putting
\section{publications}
\otherlanguage{russian}
\small{Сборник тезисов докладов VI научной молодежной школы-конференции
«Химия, физика, биология: пути интеграции», 2018, 82--83.}
to the end of the template prints this bibliographic entry just fine.
If your CV is in Russian then you'd want to use
\usepackage[russian]{babel}
and omit the \otherlanguage{russian}
altogether.