You can customise your own icons in its place. We actually replaced the old Font icons with inbuilt Font pack. The font icons was 1.6 mb data loaded on all the pages.

Following code sets the icon. Check the last case Default. I downloaded the svg icon from feathericons.com and replaced the default icon with the SVG.

add_filter('wplms_get_element_icon',function($icon,$type){
  switch($type){
        case 'slides':
            $icon = 'vicon vicon-layout-slider';
        break;
        case 'audio':
            $icon = 'vicon vicon-microphone';
        break;
        case 'video':
            $icon = 'vicon vicon-video-camera';
        break;
        case 'multimedia':
            $icon = 'vicon vicon-video-clapper';
        break;
        case 'textarea':
            $icon = 'vicon vicon-text';
        break;
        case 'upload':
            $icon = 'vicon vicon-upload';
        break;
        case 'dynamic':
          $icon = 'vicon vicon-control-shuffle';
        break;
        case 'static':
          $icon = 'vicon vicon-exchange-vertical';
        break;
        default:
            $icon = '<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-file-text"><path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"></path><polyline points="14 2 14 8 20 8"></polyline><line x1="16" y1="13" x2="8" y2="13"></line><line x1="16" y1="17" x2="8" y2="17"></line><polyline points="10 9 9 9 8 9"></polyline></svg>';
        break;        
    }
    return $icon;
});

Similarly you can do for all other cases as slides, audio, etc.

Let me know if you need further help.

added this code in your wplms customizer plugin changed icons : 

add_filter('bp_course_get_full_course_curriculum',function($curriculum){
foreach ($curriculum as $key => $c) {
if($c['type']=='quiz'){
$curriculum[$key]['icon'] = 'task';
}else{
if($c['type']=='unit'){
$etype = wplms_get_element_type($c['id'],$c['type']);
if($etype=='video'){
$curriculum[$key]['icon'] = 'video';
}else{
$curriculum[$key]['icon'] = 'text-document';
}


}

}
}
return $curriculum;
},999999);

fixed video units but currentl[y we are checking if can do this on course status as well.

The same function works for course curriculum;

add_filter('wplms_get_element_icon',function($icon,$type){ 
    if(empty($type) || $type == 'general'){ 
$icon = 'YOUR SVG ICON CODE'; } return $icon; },10,2);

https://prnt.sc/QL_SgSgSnBXF

 https://prnt.sc/EPwH8CrhWyTG

added this code in your customizer plugin : 

add_action('wp_head',function(){ wp_enqueue_style('font-awesome', VIBE_URL.'/assets/fonts/font-awesome.min.css',array(),WPLMS_VERSION); ?> <style> .course_timeline ul .video:before {content: "\f26c";font-family:fontawesome !important;-webkit-text-stroke: 1px;padding-left: 15px;font-size: 30px;font-style:normal !important;}

.course_timeline ul .play:before {content: "\f26c";font-family:fontawesome !important;-webkit-text-stroke: 1px;padding-left: 15px;font-size: 30px;font-style:normal !important;} .course_timeline ul .text-document:before {content: "\f0c5";font-family:fontawesome !important;-webkit-text-stroke: 1px;padding-left: 15px;font-size: 30px;font-style:normal !important;} .course_timeline ul .task:before {content: "\f044"; font-family:fontawesome !important;-webkit-text-stroke: 1px;padding-left: 15px;font-size: 30px;font-style:normal !important;} .course_timeline ul li.quiz:nth-last-child(1) .task:before {content: "\f11e";font-family: fontawesome !important;-webkit-text-stroke: 1px;padding-left: 15px;font-size: 30px;font-style:normal !important;}</style> <?php });

add_filter('bp_course_api_course_curriculum_unit',function($unit){ $unit_type = wplms_get_element_type($unit['id'],'unit'); if($unit_type=='video'){ $unit['icon'] = 'play'; }else{ $unit['icon'] =  'text-document'; } return $unit; });

add_filter('bp_course_api_course_curriculum_quiz',function($quiz){ $quiz['icon'] = 'task'; return $quiz; });

Ok added this code : 

add_filter('wplms_get_element_icon',function($icon,$type){

if($type =='static' || $type=='dynamic' || $type=='h5p_quiz'){
$icon='task';
}else{
if($type =='play' || $type=='video'){
$icon='play';
}else{
$icon='text-document';
}
}

return $icon;
},10,2);

done

Please try adding this custom css in your wp-admin-> appearance-> customize -> custom css : 

.course_curriculum_wrapper .curriculum_item>span:first-child strong{
    display:flex;
    align-items:center;
}

I put css in customize -> custom css. 

Well right now on customize page error appearing : https://prnt.sc/jBbBxlZTVhKj

need ftp of this staging to check what is wrong ?

Please increase your php memory limit to 256MB 

well there some modules loading in customizer that needs more php memory causing this issue . 

increasing php memory to 512 MB is fine 

Well no then it will not work .

You can choose memory limit to be 256b , that should fix your issue in customizer .

also you site is in staging when yo go lie you maybe able to put 512Mb as memory limit (confirm wit h webhost)