Usually, the Sumerian Gods are the same Gods of all other ancient pagan cultures, having their own pseudonyms and myths in Sumerian and Akkadian sources. Due to the fact that these civilizations, in general, are very ancient, the Necronomicon literally means “the book of forgotten names,” that is, the names-mantras of the Gods that were used as words of power, but that was “long ago.”
In this case, your Guardian may have a Sumerian origin and name, but in this case you can also find the same God in other pantheons under a different name. Since all ancient pantheons describe the same creatures - the Gods and Demons of Duat.