I mix my cats' food half raw (homemade, nutritionally complete) and canned, Wellness being one of them and my cat food sits out for 12 hours while we are gone to work and have never had a sick cat.
I wouldn't worry too much about her not eating the raw mix right away, she may not be too hungry right now. When I was transitioning Puddles, she had to get quite hungry before she would eat the Wellness (from kibble diet). You are doing the right thing by slowly increasing the raw proportion.
Good luck and don't give up, or in too quickly.