*drum roll*
With great relief, I will report my above theory worked without a hitch. The 2 lines are connected via a 50amp inline fuse, and all my non-functioning systems now greet me with their warm Orange displays and working motor functions. HOORAY I get to keep my 2nd favorite car.
A thousands thanks DanOKC for sticking it out with me, had your posts not kept bringing me ideas and hope, the car likely would be in the hands of a non-enthusiast by now. merci merci
I suppose in the seemingly off chance this happens to anyone ever again, Below are the 2 wires I connected with an inline 50amp fuse. My first thought was that the black cable was a ground, though it is not, its a positive cable that runs from the front fusible link. The red cable directly powers the rear power distribution box, it requires a 50amp fuse though, to protect your GM and RM.

Now I know, there are in fact 2 ways of getting power to the rear distribution box in E34's. One way I still have not figured out yet though

But I do know where that other positive cable goes, and its behind a lot of dashboard, I think ill leave it be for now
