ok – ich sehe jetzt dein child-theme aktiv.
Wie erklärst du dir, das wenn ich in deiner Privacy die google webfonts erlaube – die schrift dann angezeigt wird?
dinpro-light steht oben mit dinpro-light() – da muss was beim generieren schief gelaufen sein. Ausserdem ist in deinen @font-face rules nur die din-alternate-cdnfonts zu sehen.
Man sieht das child-theme natürlich im Source Code – allerdings, nur bei den css und js files die auch davon herrühren: also z.B.

<link rel="stylesheet" id="avia-style-css" href="https://marcusjeroch.de/wp-content/themes/enfold-child/style.css?ver=6.0.9" type="text/css" media="all">
<link rel="stylesheet" id="style-name-css" href="https://marcusjeroch.de/wp-content/themes/enfold-child/style.css?ver=6.7.2" type="text/css" media="all">

Lass die Nutzung der oberen Webfonts (ausser den Websafe Fonts ausser acht. Lade die gewünschten Schriften hoch.
Also z.B deine DINPro und die OpenSans. Deine Open-Sans sollte funktionieren die ist dort richtig gelistet (allerdings nur als ttf )
Schmeiss deine DINPro aus dem Font Manager raus und lade diese mal hoch: https://webers-testseite.de/DINPro.zip
Die wird dann dort gelistet:

Wähle dann unter General Styling – Fonts diese Schriften aus (bei den Hochgeladenen Schriften unten)

Du benötigst dann nicht mehr die Auflistung in der Privacy – da selbstgehostete Fonts verwendet werden.

you can find all demos on GitHub Library: Link

download the zip file you need. Extract the xml file of it and look for the needed enfold shortcode of the wanted page — easiest way: search for the page ID as: post_id>206 or finding the home page on that demo search for: CDATA[home]

copy the needed enfold shortcodes from :

<content:encoded><![CDATA[  
… here is the avia shortcode inside
]]></content:encoded>

this copied shortcodes you can enter on a new page inserting it to the debug mode input field (activate the debug mode on : Layout Builder – Debug Mode (Backend Only))
save that new page – now you have copied all the layout of the wanted page.

You had to edit now that page elements to enter your image/media links inside that code.

i see this in your DOM:

no child just enfold.

next: see if i switch on the usage of google web fonts via your privacy settings:
https://webers-testseite.de/jeroch.mp4

on your @font-face rules a lot of open-sans and one Din font:

activation of uploaded Fonts : the list of uploaded fonts is at the end of that enfold list:

something went wrong with your uploading ( on that child-theme with dinpro-light ) –
and yes i have seen that on your video the child was activate ( but now the theme itself is in use)

on transparency – there will be no breadcrumb – see functions-enfold.php:

if(!empty($transparency)) $header['header_title_bar'] = 'hidden_title_bar';

but you can place it via a shortcode –
see snippet and usage on : https://webers-testseite.de/breadcrumbs-shortcode/

First of all – your business location is Germany – so you had to be GDPR (DSGVO) compliant.
For that reason – do you have any entrance inside your theme to hamper google font support of the theme. F.e. via a snippet plugin?
like:

function my_output_google_webfonts_script( $activate ){
  return false;
}
add_filter( 'avf_output_google_webfonts_script', 'my_output_google_webfonts_script', 10, 1 );

OR

function enfold_customization_switch_fonts() {
    global $avia;
    $avia->style->print_extra_output = false;
}
add_action( 'init', 'enfold_customization_switch_fonts' );

you only uploaded open-sans and din-alternate-cdnfonts

Next question: on your video i see that you are using a child-theme – but on your live site i do not see that you are using it?

ON your Privacy setting : if i accept using Google Web fonts i see:

my recommendation on GDPR compliance : use selfhosted fonts – upload them via font-manager as you did with open-sans.
Then you do not need to mention the google webfont usage hint on privacy.

Dear Mercedes salesman, could you please tell me if other cars are just as good and which one I should buy instead? Really now?
Enfold is also a for-profit business. As a participant, I think I’m allowed to say this; I hope you don’t mind.

on https://kriesi.at/themes/enfold-2017/elements/magazine/ you want to preserve the bigger image post and have on the smaller images a two column view?

to have:

you can have this by css only – but you had to break earlier to responsive case to have enough space for showing the articles with smaller images:

#top .av-magazine-sideshow:before,
#top .av-magazine-sideshow:after {
  display: none;
}

#top .av-magazine-sideshow {
  display: flex;
  flex-flow: row wrap;
  justify-content: space-between;
}

#top .av-magazine-sideshow .av-magazine-entry {
  flex: 0 1 48%;
  width: unset;
}