Little bug in "mod_easysocial_pages"

Hello guys. So you have this module mod_easysocial_pages which display pages from EasySocial.
It works great. But there is one issue.

It downloads pages backgrounds in full size. It increases webpage download speed A LOT
I have 4 groups in this module only - but it's already almost 2 extra mb of data. Look at the screenshot


Here is line from this module code :

<div style="background-image : url(/<?php echo $page->getCover()?>;

				background-position : <?php echo $page->getCoverPosition();?>" class="mod-card__cover">

I did check, for every page background you have different versions:

• _thumbnail
  
• _stock
  
• _large
  

In our case by request $page->getCover()? we are getting " _large"
Tell me please, how can I request for "_thumbnail" version of the picture?

P\s I tried to find it in Mysql but no results. That's why I'm asking you

Do you have some documentation with all this $page->(something)?
Because more I working with EasySocial more small bugs I'm finding. I don't want to disturb you every time =)