Keep practicing mate, you'll get it. I think it was Shadiversity on Youtube that said swords couldn't be drawn from the back at all, and he had to correct himself.
Its not a practice issue. The scabbard is not made for backdraw. Hince it doesnt work. Backdraw needs a specialized scarbbard, like i said in my op

True, but you also said in your op that they couldn't be made w/out modern tech.
No i didnt? I think you read that into it

I say nothing about how they are made, tools materials etc.
They (back-scabbards) are however a modern invention. DnD and Witcher are fantasy and has very littel to do with history, so thats totaly fine. All im saying is that its modern invention special equipment (that could be made with medieval style tools and tech).