Hi, my name is Guillermo Antony Cava Nuñez, recently been swamped with work. One of the dilemmas I had to figure out how to solve was the issue of being able to run an express backend for one of the apps we are developing. These couple of lines were a lifesafer. Hope they are as helpful to you as they were to me.
WHM -> Apache Configuration -> Include Editor -> Pre VirtualHost Include -> All Versions
<VirtualHost ip:80>
ServerName domain.com
ProxyPreserveHost On
ProxyPass / http://localhost:8080/
ProxyPassReverse / http://localhost:8080/
</VirtualHost>
For more info, check the documentation