Casaubon's 1659 printing preserves The Second Call in the angelic language Dee and Kelley called the language of Enoch, set beside Dee's own English gloss line by line, the same format Casaubon used for the whole corpus of forty eight keys. That parallel text is the entire textual basis for everything known about the call: no independent manuscript tradition confirms or corrects it beyond Dee's own diary pages.
The language itself has drawn sustained argument since Casaubon's day over whether it is a wholly invented tongue, an elaborated cipher built on English and Latin grammar, or something closer to a constructed language with its own internal consistency. That argument belongs to the corpus as a whole rather than to The Second Call specifically, and it is why modern editions still print the angelic text and Dee's gloss side by side rather than treating either as sufficient on its own.
Twentieth century ceremonial orders revived the Calls for practical use largely through the Golden Dawn's Enochian curriculum and, later, through Aleister Crowley's own scrying of the thirty Aethyrs using the nineteenth call, recorded in his 1911 Vision and the Voice. The Second Call, as one of the two general keys, has a smaller footprint in that later literature than the nineteenth call itself, since it opens a working rather than addressing any one of the thirty Aethyrs those later magicians focused on.