I do not have a large amount of information on this, but no, I think this is normal for Callery pear seedlings, most of them, or most apples are compatible, winter banana and Apple-Pear Cross are both highly compatible with pears, but Crispen aka Mutsu, and Mott’s Pink (possibly actually Cripp’s Pink) don’t have any special pear properties, and unfortunately an unknown apple, perhaps Evercrisp, also was my first successful apple graft test on this tree, but it was so high up, I decided to cut the tree down low and redo it down low, especially since I have that apple grafted in dozens of branches and trees in my orchard.
Also there’s another of these seedlings that that apple and Apricot Apple were both successful on.
A deer broke the “Evercrisp”, and I cut it down to the ground and regrafted it with Apricot Apple in the end, when I left, it was growing well even after being cut back and being re grafted late in the season.