Hmm. There is no searchable EG4 on the Sol-Ark website. The warranty makes no mention of voiding with EG4 batteries.
What I do strongly believe is that Sol Ark will provide technical support for persons who have the batteries Sol Ark has partnered with on their website. Otherwise, they specifically state that their inverter is battery agnostic. But the installer will have to make the connections and set the language protocol and see if they can get their battery to work. Sol Ark will not spend resources doing this for you.
So please, when you make this comment, understand that in some states, the governing law creates warranty rights and if you have not been told this directly by Sol Ark, do not post it unless you can back it up. Otherwise, you just look like an EG4 customer.