Hi
Try drawing the design onto your jean fabric. When I want to trace a pattern I tape it to the window, (overlapping the ends of the tape so I can get it off)and put another piece on top of it and tape that, and draw or trace it. I know its fabric but you should be able to see it. Do it in bright daylight.
Another idea. Can you get a print out on your design? Print template, or a copy of it. Put tracing paper on the bottom, making sure you have the correct side up. lay fabric single layer, or two layers , lay tracing paper between layers. Have your template on top of the fabric and trace it.
I hope I helped you some or gave you an idea. B.

I embroider on jeans too.

If I'm using a template, I use a sharpie to mark the design. It won't wash out, but I stitch over the marks anyway.

For tracing, I trace onto tissue paper, then pin the tissue paper to the jeans and stitch the design through the tissue paper. Remove the tissue paper carefully when you're finished. If your pattern is really intricate, you might want to trace different parts of the design onto different sheets of tissue paper.

Try using something like Solvy! It's great for this kind of thing. You can see how it works here:

Here is a link that might be useful: NeedleNThread