Section with different font sizes AND author with more than one affiliation

Question

I'm new to LaTeX and I have two doubts concerning this paper template that was provided by the congress: Paper Template - Overleaf.

1 Doubt (not solved): They say that the first letter of the headings must be 12pt and the other 8pt. When I generate the PDF file and open it using my PDF reader, the first letter size is ok, but the others are something around 9, 9.5, or 10pt. How can I solve this?

The image below shows what I want (blue, with the first letter 12pt and others 8pt) and what I got after compiling (black, with the first letter 12pt and others 10pt).

The .cls file contains this codes about \section:

\renewcommand\section{\@startsection {section}{1}{\z@}%
                                   {-3.5ex \@plus -1ex \@minus -.2ex}%
                                   {2.3ex \@plus.2ex}%
                                   {\center \large \textsc}}
\renewcommand{\thesection}{\Roman{section}.\hspace{-3mm}}

2 Doubt (solved): I've tried (without success) to add two affiliations to the same author. To solve it I've added the following code to the .cls file, according to this post.

\renewcommand{\author}[3][]{
      \stepcounter{ifmbe@authors}
      \expandafter\def\csname ifmbe@author\alph{ifmbe@authors}\endcsname
      {#2$^{\expandafter\the\csname ifmbe@affiliationcounter#3\endcsname
        \if\relax\detokenize{#1}\relax\else,#1\fi}$}
}

So, I've done the following in my main.tex providing the figure below.

\documentclass[nouppercase]{ifmbe}
\title{Paper Title - XXX YYY Congress - 2022}
\affiliation{Department of Electrical Engineering, University of Somewhere, City, Country}{FIRSTAFF}
\affiliation{Department of Mechanical Engineering, University of Somewhere, City, Country}{SECONDAFF}
\author{First Author}{FIRSTAFF}
% changed from \author{Second Author}{SECONDAFF} to:
\author[2]{Second Author}{FIRSTAFF}
\begin{document}
\maketitle
\begin{abstract}
This paper presents instructions for preparing papers. The template is intended to guide the authors in  preparing the electronic version of their paper. Only papers prepared according to these instructions will be published in both, the paper and online version. In this abstract section you should provide an abstract of your paper, not longer than 300 words.
\end{abstract}
\end{document}

Thanks.