Remove bottom space from colum and place text right to image / how to reduce spa

set on first try that second column row to not show as equal height.

try to change that one rule to:

(it is only that line changed: grid-template-columns: auto 1fr; )

#top .avia_textblock.img-with-caption-right .wp-caption {
  border: 1px solid #cccccc;
  width: 100% !important;
  margin: 0;
  display: grid;
  grid-auto-rows: auto;
  grid-template-columns: auto 1fr;
  grid-template-areas:
"feld2 feld1";
  align-items: flex-end;
}

ok –
put this to your child-theme functions.php:
(try if the window on load is neccessary)

function set_class_for_image_orientation(){
?>
<script>
(function($) {
  $(window).on('load', function(){
    var images = document.getElementsByTagName('img');
    for( var i=0; i<images.length;i++){
      if(images[i].naturalWidth > images[i].naturalHeight) {
        $(images[i]).addClass('landscape');
      }
      else if (images[i].naturalWidth < images[i].naturalHeight) {
        $(images[i]).addClass('portrait');  
      }
      else {
        $(images[i]).addClass('square-image');
      }
    } 
  });
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'set_class_for_image_orientation');

now every image got a class on img that belongs to its orientation

then place that code to your quick css:

#top .avia_textblock.img-with-caption-right .wp-caption img.portrait {
  margin-top: 0
}

and perhaps you like to go back to the same width if responsive case (smaller than 767px)

@media only screen and (max-width: 767px) {
  #top .avia_textblock.img-with-caption-right .wp-caption {
    grid-template-columns: 1fr 1fr;
  }
}

you could go and set that one rule for non responsive case :
(grid-template-columns: 35% 65%;)

#top .avia_textblock.img-with-caption-right .wp-caption {
  border: 1px solid #cccccc;
  width: 100% !important;
  margin: 0;
  display: grid;
  grid-auto-rows: auto;
  grid-template-columns: 35% 65%;
  grid-template-areas:
"feld2 feld1";
  align-items: flex-end;
  overflow: hidden;
}

But you had to manually insert softhyphens to some of your titles.
By the way: Self Contained and on the one image Selfcontained ?

It is difficult to fulfill all your requirements because the preconditions are of course not identical. Different image formats and aspect ratios paired with titles of different lengths.

if you see this page – that has your initial setting with text-blocks in columns (equal height ) – images floating left and text directly behind it.
But you see on last column row – that with equal height option the space to top is much bigger than on the other images besides other landscape images.

https://webers-testseite.de/jak73/

Password: is the last name of that logo ( capitalize )

if you like to hold that solution – you can erase that code. ( it is based on a different custom class. )
hold the img-with-caption and blue-info css !

on inserting the images to the text-block – i edited the images – and gave them all the same width (250px)

Next: It might be best to switch to responsive design on 989px ( even for your menu too )