Special characters not displaying

UPDATE: the given characters aren't included in the font file (provided by client) :)

I have a site where I use locally hosted fonts, all of them should be latin-ext. on the site bold special characters ő, ű aren't displayed, though they are included in the character set.

What do I need to do to have these displayed? Is there a special setting I'm missing?

Thank you for any insight.

This is what I have in the style.css:

/* Brandon Grotesque - Bold */
@font-face {
font-family: 'Brandon Grotesque';
src: url('/wp-content/themes/franciska_new/fonts/BrandonGrotesque-Bold.woff2') format('woff2'), 
    url('/wp-content/themes/franciska_new/fonts/BrandonGrotesque-Bold.woff') format('woff');
font-weight: 700;
font-style: normal;
font-display: swap;
}

/* Brandon Grotesque - Bold Italic */
@font-face {
font-family: 'Brandon Grotesque';
src: url('/wp-content/themes/franciska_new/fonts/BrandonGrotesque-BoldItalic.woff2') format('woff2'), 
    url('/wp-content/themes/franciska_new/fonts/BrandonGrotesque-BoldItalic.woff') format('woff');
font-weight: 700;
font-style: italic;
font-display: swap;
}

This is my functions.php:

/* add fonts to customizer */
add_filter( 'generate_typography_default_fonts', function( $fonts ) {
    $fonts[] = 'Brandon Grotesque';
    $fonts[] = 'Lato';
    $fonts[] = 'Montserrat';
    $fonts[] = 'Alice';
    $fonts[] = 'Playfair Display';

    return $fonts;
} );