Repeating the same footnote reference on different pages for biblatex-gost footnote style

Question

I need to repeat footnote references on each page instead of creating lots of footnotes with references to previous footnotes. I found this answer which looks like it does exactly what I want except that I'm using gost-footnote style:

\usepackage[
  style=gost-footnote,
  maxcitenames=3,
  maxbibnames=100
]{biblatex}

With this style using the code from that answer directly does not work because it can't find cite:init, cite:comp and other macros. I tried to adapt it to gost-footnote by looking to the latter's footcite implementation and came up with this:

\DeclareCiteCommand{\sfcite}[\cbx@superscript]
  {\let\multicitedelim\supercitedelim%
   \usebibmacro{prenote}}
  {\usebibmacro{citeindex}%
   \usebibmacro{cite:super:foot}}
  {}
  {\usebibmacro{cite:postnote}}

However, it does not work correctly. That is, it does seem to show footnotes exactly in the order I want, but all actual numbers, both in text and in footnotes disappear:

Additionally, it somehow breaks separators. The following redefinition works with vanilla footcites:

\renewcommand{\newunitpunct}{\adddot\space---\space}

but stops with sfcite.

How do I solve these issues? My TeX knowledge is not enough to deal with these arcane macros :(

Here is an example document which shows the problem:

\documentclass[oneside]{scrbook}

\usepackage[T2A]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[russian]{babel}

\usepackage[
  style=gost-footnote,
  autocite=footnote,
  autopunct=false,
  maxcitenames=3,
  maxbibnames=100
]{biblatex}

\makeatletter
% user-level citation command
\DeclareCiteCommand{\sfcite}[\cbx@superscript]
  {\let\multicitedelim\supercitedelim%
   \usebibmacro{prenote}}
  {\usebibmacro{citeindex}%
   \usebibmacro{cite:super:foot}}
  {}
  {\usebibmacro{cite:postnote}}

% save instcount, save key and last inline instcount if seen first on page
\newbibmacro*{cite:super:foot}{%
  \xdef\cbx@key{\thefield{entrykey}}%
  \ifsamepage{\value{instcount}}{\csuse{cbx@instcount@\cbx@key}}{}{%
    \listxadd{\cbx@savelist}{\cbx@key}%
    \ifnumequal{\value{cbx@tempcntd}}{0}{%
      \defcounter{cbx@tempcntc}{\value{instcount}}%
      \loop\ifnum\value{cbx@tempcntc}>0
        \ifsamepage{\value{instcount}}{\value{cbx@tempcntc}}
          {\ifcsundef{blx@fnpage@\number\numexpr\value{cbx@tempcntc}}
             {\setcounter{cbx@tempcntd}{\value{cbx@tempcntc}}}{}%
           \stepcounter{cbx@tempcntc}}
          {\setcounter{cbx@tempcntc}{0}}%
      \repeat}{}}%
  \csnumgdef{cbx@instcount@\cbx@key}{\value{instcount}}}
\let\cbx@savelist\@empty
\newcounter{cbx@tempcntc}
\newcounter{cbx@tempcntd}
\setcounter{cbx@tempcntd}{0}

\newrobustcmd*{\cbx@superscript}[1]{%
  \global\toggletrue{cbx@sfcite}
  \mkbibsuperscript{#1}%
  \cbx@footnote%
  \global\togglefalse{cbx@sfcite}}
\newtoggle{cbx@sfcite}

\AtEveryCitekey{%
  \ifciteseen{}{\csnumgdef{cbx@instcount@\thefield{entrykey}}{-1}}%
  \iftoggle{cbx@sfcite}{}{\cbx@footnote}}
\AtEveryBibitem{\cbx@footnote}
\AtEveryLositem{\cbx@footnote}

% defer citation footnotes to last inline reference instance on page
\newrobustcmd*{\cbx@footnote}{%
  \ifboolexpr{ not test {\ifdefempty{\cbx@savelist}}
               and test {\ifnumequal{\value{instcount}}{\value{cbx@tempcntd}}} }
    {\cbx@sortlist@init%
     \let\do\cbx@do
     \dolistloop{\cbx@sortlist}%
     \global\let\cbx@savelist\@empty
     \setcounter{cbx@tempcntd}{0}}{}}

% print footnotes in 'sorting' order
\def\cbx@do#1{%
  \ifinlist{#1}{\cbx@savelist}
    {\begingroup
     \blx@resetdata
     \blx@getdata@cite{#1}%
     \blx@setoptions@type\abx@field@entrytype
     \blx@setoptions@entry
     \blx@execute
     \blx@beglang
     \iffieldundef{shorthand}
       {\gdef\@thefnmark{\printfield{prefixnumber}\printfield{labelnumber}}}
       {\gdef\@thefnmark{\printfield{shorthand}}}%
     \gappto\@thefnmark{\blx@initunit}%
     \ifhyperref
       {\H@@footnotetext{\blx@driver\abx@field@entrytype}}
       {\@footnotetext{\blx@driver\abx@field@entrytype}}%
     \blx@endlang
     \endgroup}
    {}}

% access internal list of sorted entry keys
\def\cbx@sortlist@init{%
  \ifcsundef{blx@sort@\the\c@refsection}
    {\global\letcs{\cbx@sortlist}
       {blx@slists@\the\c@refsection @entry@\blx@sorting}}% Biber
    {\global\letcs{\cbx@sortlist}{blx@sort@\the\c@refsection}}}% BibTeX
\let\cbx@sortlist\@empty
\makeatother

\addbibresource{biblatex-examples.bib}

\usepackage{fnpct}
\AdaptNoteOpt\sfcite\multfootcite

\renewcommand{\newunitpunct}{\adddot\space---\space}

\begin{document}

\toggletrue{bbx:gostbibliography}

\pagestyle{plain}

\null\vfill

Example \sfcite{bertram}\sfcite{doody}, example \sfcite{gillies}

\end{document}