Well, Wikipedia says, ". . . a commercially marketed brand of Fuji or Gala apple. . . A Grapple is created by infusing an apple with a concentrated solution of natural and artificial Concord grape flavor and water."
So, you realize that you have planted an apple seed that will not taste like a Concord grape unless you injected it, yourself.
Apple varieties are propagated by the grafting of cuttings and not by seeds. This is probably also true of Asian pears. This is perpetuates clones of an original tree that was thought to have special and valued properties. Seed from the trees may result in seedlings that are quite different from their parents.
I don't know anything about starting Asian pears and apples from seed. I do, however, have a peach tree that began life as a seed. The fruit, fortunately, is wonderful. I have had an orchardist tell me that it is just ike Blushing Star white peaches. I don't know if the tree itself has those characteristics and am just thankful that it turned out to be something useful. I don't know what the odds were of that, however.
Starting soil is for just that - starting seed. The expectation is that the seedling will be moved to a different mix when it is quite young. Often, there is no actual soil in the starting mix and no fertilizer, either.
Perennials like trees and other plants often don't make much growth during their first year of life. Generally, they need to be in the ground or have quite large containers so that they can develop a root system adequate for a lot of future growth.
Personally, I think it is time to move the plants to where they will have adequate soil nutrients.