Recent versions of the Essential mod added compatibility with FancyMenu, which means you should now be able to fully customize all elements Essential adds to the Title screen and Pause screen!
For a detailed guide about how to customize Essential's UI, you should take a look at this wiki page of the Essential wiki!
If you encounter some bug or inconvenience while trying to customize Essential's elements, it is almost always caused by Essential and the Essential devs need to fix it on their side.
You should report the bug/issue to the Essential team via their Discord or GitHub.