I have to tell you, I did not like my one attempt at home dec sewing at all. It was a roman shade, and I ended up putting it off a lot..and in the end the shade did not fit the window due to a calculation error.
In theory I could fix it, but a really don't feel like it. I just felt out of my element working with something so big, and with those long, straight lines. Anyway, that does not at all mean that YOU won't like it, but don't feel obligated to do this just because your friend cannot sew and for some inexplicable reason felt compelled to take on a sewing project.
On thing to consider is that her choice of fabric may not be easy to sew. That outdoor canvas-type stuff is pretty thick, and not all machines can handle it. I know my Singer machine isn't too happy with me when I try to sew even medium weight denim. So, before you say yes or no, you might want to test a swatch to see if you can get it to work at all.
It seems like you could probably figure out a no-sew solution - perhaps if she doesn't care about what the cushions look like in the back, she could cover the fronts with pieces of fabric and use adhesive velcro to hold the cover on. The edges of the fabric could be finished by turning under twice and using fusible tape to hold the hem. Or, if she doesn't care if the covers are removable, she could just cover the fronts of the pillows and staple or hand sew to the existing fabric in the back. I have no experience with this sort of thing, so don't take my word for it..but just a few ideas to think about.