Who are Faltines (Dormammu like beings) really, is there any mention of their dimension in MCU comics?

In Doctor Strange, we are told about Dormammu, a creature residing in the Dark Dimension, feeding upon matter. Apparently he’s part of a species known as the Faltines.

The Marvel Wiki article on Dormammu mentions that he and another (Umar) were born out of Sinifer, who used to feed on energy only. But the new Faltines fed on matter and ended up eating Sinifer which made all other Faltines furious and both Dormammu and Umar were exiled to the Dark Dimension.

So where was Umar when Dormammu came to Earth? And is there any mention of the Dimension of the Faltines in the MCU movies or more importantly MCU comics?