When I first got started in bowmaking I ordered a box of supplies from 3rivers. In that box was a spool of artificial sinew. I thought I would use it on everything. I still have that spool and it is still about 99% there. I used some to tie something up in the garage one time. I have never found the need to use any when making bows, especially for backing them. I could see were it would work well on leather crafts so maybe I'll hold on to it.
I would imagine a bow backed with artificial sinew would be similar to a bow backed with real sinew and TB glue. It would offer protection, but very little in the way of performance. Just my thoughts on it as a backing