first – did you copy&paste it?
because the code here: Link has wrong quotation marks.

The code above can’t affect the logo area.
The function ( trimByWord ) that is defined there is exclusively then applied below to selectors that are not used in the logo or even header.

please just let a mod look into your installation. I suspect that it is due to something completely different.
My support on this topic is now over.

btw – if you load the jQuery in the footer:

then you must change the code by loading it in the wp_footer too! – last line:

add_action('wp_footer', 'custom_excerpt_setting');

I know that you write above that it was not so with the previous version. But often you forget that you have also run other plugin updates. – If you restore the older version now, do you not see the problems anymore?

_______
well if you look at: https://gtmetrix.com/reports/cdmercercontractors.co.uk/T9HHuSwk/

you see that the TTFB ( Time to first byte ) is large – contact your provider and ask what could be the reason for it.
maybe look to your site’s current memory limit – it is set in the wp-config.php file and may not match the limit allowed by your provider.
you can look into Layerslider WP – Options – System Status – Server Settings:

if it might be too low – put this code to the appropriate position ( f.e. under the WP_DEBUG setting ) :

define( 'WP_MEMORY_LIMIT', '256M' );

but isn’t there an option to mark that on new posts or comments etc the cache will be refreshed automatically?

can you please replace that jQuery Code and replace it by this:

function custom_excerpt_setting(){
?>
<script>
(function($){
// trim excerpt by words
    function trimByWord(sentence,wordcount = 10) {
        var result = sentence;
        var resultArray = result.split(" ");
        if(resultArray.length > wordcount){
        resultArray = resultArray.slice(0, wordcount);
        result = resultArray.join(" ") + "...";
        }
        return result;
    }
    $(document).ready(function(){
        $('.avia-content-slider .read-more-link').each(function() {
            $(this).parent().parent().append($(this));
        }); 

        $('.avia-content-slider .slide-entry-excerpt').each(function() {
             $(this).text(function(index, currentText) {
                return trimByWord(currentText);
             });
        });
    });
})(jQuery);
</script>
<?php
}
add_action('wp_head', 'custom_excerpt_setting');

Edit : if you load jQuery in your footer ( see Enfold – Performance : “Load jQuery in your Footer” ) the whole had to be loaded in the footer too – and after jQuery is loaded. Last line should be replace by:

add_action('wp_footer', 'custom_excerpt_setting');

and with the css code from beginning – you see that now the slide-meta like the date is then in one line at the bottom:

#top.blog .avia-content-slider .slide-entry-wrap {
  display: flex;
  flex-flow: row wrap;
}

#top.blog .slide-content {
  padding-bottom: 60px;
}

#top.blog .entry-footer {
  display: ;
  position: absolute;
  bottom: 0;
  top: auto;
}

yes – and i comment in that code above ( jquery code ) that i do not see your page you are referring to. This line in the code :

$('.av-masonry-entry .av-masonry-entry-content').each(function() {

had to be adjusted to the selectors that will work on your page – i can not give better advice if i do not see the concrete page it concerns
and since I am a participant like you I do not see the link if it is in the private content area.

but the filter you decided to use is ok. – maybe it is just a matter of the accepted args value – leave without that:

function avia_change_masonry_excerpt_length($length){
	$length = 200;
	return $length;
}
add_filter('avf_masonry_excerpt_length','avia_change_masonry_excerpt_length', 10 );

you mean on a page like this: https://kriesi.at/themes/enfold-2017/blog/blog-default/

Is it your intention to have same-height blocks? For that you do not need to have the samel excerpt length?

you can position those buttons absolute.
Best would be to give to the color-section a unique ID – or a custom class.

The code below is with your default ID on this : #av_section_2 – but to avoid that every section_2 will do that on other pages – see above.

#av_section_2 .flex_column .avia-button-wrap {
  position: absolute;
  bottom: 0 !important;
  padding: 20px 0;
}
#av_section_2 .flex_column .av_textblock_section {
  padding-bottom: 40px;
}

The space now occupied by the button – must be added to the last element in front of it – here the text block – as padding-bottom.

Maybe you decide to give the headings a min-height for screens larger than the responsive case ( in your installation 768px )
f.e.:

@media only screen and (min-width:768px){
  #av_section_2 .flex_column .av_textblock_section h5 {
    min-height: 50px
  }
}

only if there are three lines of heading – this will not result in the alignement.

did you have the last Enfold installed?
because magazine has this too on 4.8.6.3.: https://kriesi.at/support/topic/error-25/#post-1322781
or update to 4.8.6.5

go and look if on line 464 from postslider.php there is only:

if( 'disabled' == $atts['img_scrset'] )

and try to replace it with:

if( isset( $atts['img_scrset'] ) && 'disabled' == $atts['img_scrset'] )

You want to apply flexbox model as here – and set parent element ( entry-content-wrapper ) to display flex? But in my opinion this requires to keep the flex columns exclusively in an enclosing ( color-section ) container. Then it would be enough to set the flex-flow to row wrap-reverse on responsive case. Otherwise, properties would still have to be assigned to the flex items.
With grid-row this is automatically the case – each flex-cell row is separate from other flex-cells. See: https://webers-testseite.de/reverse-order/
See the example page with one color-section ( white background ) and 6 1/3 flex-columns. On that it will be nice to have on the flex-column itself an input field with flex order number
Result you see belongs to:

@media only screen and (max-width: 767px) {
	.page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column {
		flex: 1 1 100%;
		margin-bottom: 30px !important;
	}
	 .page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(2),
         .page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(3) ,
         .page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(6)  {
		order: 1;
	}
	.page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(1),
        .page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(4),
        .page-id-38828 .avia-section.reverse-order .entry-content-wrapper .flex_column:nth-of-type(5) {
		order: 2;
	}
}

the trick will be that on responsive case this reverse order will be set in your media query ( when those columns should break to 100% width )
it only makes sense if the reverse order influences only one column row. ( yellow background )

________
Read More : https://css-tricks.com/snippets/css/a-guide-to-flexbox/
the direct parent element should be the flexbox – the first children are the flex-items.

Have a look on Google Font Inter it is a variable webfont and looks very similar to Helvetica Neue. Big Advantage is on modern browsers – that you load only one file for all font-weights – and maybe ligatures etc.
Inter goes from 100 to 900 on weight ( flexible !!! ) and on slant ( italic variants -10 to 0 )

btw. : this here is a nice online tool to get all font options from an uploaded font: https://wakamaifondue.com/

do you have Webfont formats of Helevetica Neue ( woff, woff2, ttf, svg, eot ) ?