By the way – you can open svg files with good text editors. (Sublime Text on Mac – or Notepad++ on Windows)
That’s a first hint. I opened your logo in Illustrator and created meaningful groups. I then edited these in Sublime Text. Above all, I renamed the standard Illustrator group names (manually) and assigned IDs to the groups.

But unfortunately I’ll have to put you off until after Christmas – from now on I’ll be in off-duty mode.
As I said, it’s always better for us who want to help to be able to analyze the page with the problems.

But surely you don’t want this background image to be compressed or stretched – you want to maintain the aspect ratio.

Enfold has it for a background image on: General Styling – Body Background.
If you have now selected a stretched layout, a pop-up will display a message: These options are only available if you select the ‘boxed’ or ‘framed’ layout. Your currently have a different layout selected.

So this body background-image only makes sense if you use one of those ‘boxed’ or ‘framed’ layout.
If you got one background-image in that setting – set it to cover the page.

There are possibilities to change that bg image on load by script.

__________

Mais vous ne voulez certainement pas que cette image d’arrière-plan soit comprimée ou étirée – vous voulez conserver le rapport hauteur/largeur.

Enfold l’a pour une image d’arrière-plan sur : Style général – Arrière-plan du body.
Si vous avez sélectionné une mise en page étirée, une fenêtre contextuelle affichera un message : Ces options ne sont disponibles que si vous avez sélectionné la mise en page « encadrée » ou « encadrante ». Vous avez actuellement sélectionné une mise en page différente.

Cette image d’arrière-plan n’a donc de sens que si vous utilisez l’une de ces mises en page « boxed » ou « framed ».
Si vous disposez d’une image d’arrière-plan dans ces paramètres, réglez-la de manière à ce qu’elle couvre la page.

Il est possible de modifier cette image de fond au chargement par script.

To give better advice, it is best to see the page. This also applies to the svg logo issue.

i guess that page with no Title has a transparency header.
in functions-enfold.php there is:

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

Try in your child-theme functions.php:

function custom_shrink_factor($shrink_factor){
  $shrink_factor = '95';
  return $shrink_factor;
}
add_filter('avf_header_shrink_factor', 'custom_shrink_factor');

because of avia-snippet-sticky-header.js :

const value = parseInt( shrink_factor );

Inserting fractional numbers therefore makes no sense

The mark on “Run as dry run” had to be unchecked if you like to change something to database. That was only a test run for checking if a color could be substituted this way.

Do all images got Titles or Descriptions too? – and do they differ from Alt Text?
My question is that there might be a method to generate the alt text from one of the others.

please insert this to your child-theme functions.php:
(maybe a mod knows a shorter way)

function replace_one_specific_color(){
?>
<script>
window.addEventListener("DOMContentLoaded", function () { 
(function($) {     

	function colorReplace(findHexColor, replaceWith) {
	  // Convert rgb color strings to hex
	  // REF: https://stackoverflow.com/a/3627747/1938889
	  function rgb2hex(rgb) {
	    if (/^#[0-9A-F]{6}$/i.test(rgb)) return rgb;
	    rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
	    function hex(x) {
	      return ("0" + parseInt(x).toString(16)).slice(-2);
	    }
	    return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);
	  }

	  // Select and run a map function on every tag
	  $('.flex_column, .avia-button').map(function(i, el) {
	    // Get the computed styles of each tag
	    var styles = window.getComputedStyle(el);

	    // Go through each computed style and search for "color"
	    Object.keys(styles).reduce(function(acc, k) {
	      var name = styles[k];
	      var value = styles.getPropertyValue(name);
	      if (value !== null && name.indexOf("color") >= 0) {
	        // Convert the rgb color to hex and compare with the target color
	        if (value.indexOf("rgb(") >= 0 && rgb2hex(value) === findHexColor) {
	          // Replace the color on this found color attribute
	          $(el).css(name, replaceWith);
	        }
	      }
	    });
	  });
	}
	// Call like this for each color attribute you want to replace
	colorReplace("#ea675b", "#0000DD");

})(jQuery);
});
</script>
<?php
}
add_action('wp_footer', 'replace_one_specific_color');

ok – you can try first the last tip.
Then i will have a look if we can address it by attribute selector.

you are talking about the background-color of that flex_column

this does not come from a theme setting – it is set inside the column itself. You can open that column element in the editor mode and change the background-color.

I do not recommend addressing all flex_columns with a global CSS code.

What do you mean by:

All the “.” and capitals were in the right place.

What did you enter to the alt input field f.e.?

You can see at the bottom that I have used the backcolor: #ea675b

i do not see your setting – i can see that on socket – there is the color: #081f5e
which is then saved from enfold as: –enfold-socket-color-bg

have a look at: general styling – socket – Socket Background Color

you are not talking about the blog Element of Enfold?
even a conditional logic is present to show post if the got one of those categories or only if they have all of them.