My mother-in-law lives in Oswego/Montgomery, and I just planted a similar seed mix in her backyard! I know that area can be quite clay heavy (or at least around my MIL's house), but after each fall when the wildflowers are cut back and decompose the nutrients will go back into the soil and build a healthier dirt. The flowers will also attract wildlife that will leave behind nutrients and overall lead to a healthier earth, so it should be fine for your fruit trees. The bees thank you!
I'm hoping the seeds I planted germinate okay in the clay heavy soil. Good luck to yours too!
Another thing to keep in mind is that some of those flowers won't bloom until the second year, so you'll have to wait at least one year for the beautiful Columbine's to show up.