There is the 6th world almanach but I dont think thats what you are looking for.
I had the same problem you have, when I started analysing the universe of Shadowrun a few months ago.
I feel like you have to take the onion approach to the whole thing: Get the core rulebook and read the introductions and all the fluff texts. If you find a term look it up on the internet (that will happen a lot in the beginning). If you cant find any answers, ask here

After that, focus on a particular part relevant for your gameplay. Be it the matrix, magic, a specific nation or critters, just read, look up what you dont know and ask if you dont find anything.
I think getting a complete understanding of the world as for example ourubouros has it, is impossible, but we can get to about 85% i think.
hope this helped.....