I apologize for the late response. Please follow the steps below:

1. Remove the code from the functions.php file. It's not necessary. 

2. Replace the js code provided by Elvina with the following one:

jQuery(document).ready(function ($) {
   $(document).on('click', '.wcai-short-info', function (e) {
      e.preventDefault();
      var elem = $(this);
      elem.removeClass('wcai-not-clicked');
      var attrId = elem.parents('.wpd-comment-left').siblings('.wpd-comment-right').attr('id');
      var commentId = attrId.substring(attrId.lastIndexOf('-') + 1);
      var data = new FormData();
      data.append('commentId', commentId);
      data.append('action', 'wcaiGetInfo');
      wpdiscuzAjaxObj.getAjaxObj(true, true, data).done(function (resp) {
         elem.addClass('wcai-not-clicked');
         if (resp) {
            $('#wcaiInfo').html(resp);
            $('#wcaiInfo ul.wcai-list .wcai-list-item:first-child').addClass('wcai-active');
            $('#wcaiInfo div.wcai-content .wcai-content-item:first-child').addClass('wcai-active');            if (!($('#wcaiInfo').is(':visible'))) {
               $('#wcaiInfoAnchor').trigger('click');
            }
         }
         $('#wpdiscuz-loading-bar').hide();
      });
      return false;
   });
});

1. The code is adding a class to wpd-comment-author class, while I wanted to modify the avatar behavior. It seems like the code is modifying comment author behavior.
2. The hook also seems to be adding class to Author Name & Author Avatar.

Just to repeat my question, Comment Author name link is launching the "Comment Author Info" popup & that is the correct behavior. I don't want to make any change to that behavior.

But Comment Author Avatar is a hyperlink to Author's Page. This is the behavior, I want to change where clicking on Comment Author Avatar should also launch "Comment Author Info" popup. Can you please recheck & confirm the solution?

Regards

Please follow the steps below to make it work as you want:

1. Put the following JS code in the current active theme JS file:

jQuery(document).ready(function ($) {
   $('.wpd-comment-author').addClass('wcai-short-info wcai-not-clicked');
      if (typeof wpdiscuzAjaxObj !== 'undefined') {
         wpdiscuzAjaxObj.addClassOnAuthorName = function () {
         $('.wpd-comment-author').addClass('wcai-short-info wcai-not-clicked');
     };
   }
});

Here is a good example on how to add JS code: https://www.wpbeginner.com/wp-tutorials/how-to-easily-add-javascript-in-wordpress-pages-or-posts/

2. Put the following hook in the current active functions.php file:

add_filter("wpdiscuz_ajax_callbacks", function ($response) {
   $response[] = "addClassOnAuthorName";
   return $response;
});

3. Save, delete all caches, and check again.

As shown on this demo - https://addons.wpdiscuz.com/wpdiscuz-comment-author-info/. The add-on adds different type of links on Author's Avatar Image & Name. Author's Avatar Image is a link the the Author's page while Author's Name is the popup provided by Comment Author Info Add-on.

We want both the Author's Avatar Image & Name to launch the Comment Author Info Add-on. That way if the user really needs more details on the Author, they can click on Author's name but the behavior on both avatar image click & name click should be same/consistent IMHO.

Kindly let me know, how this can be achieved.

Regards