Hey Carl, I wanna share this experienced. I usually use perfect Strawberry as base plant for splicing normal quality. So far the plant that was not successfully grafting are Bird of Paradise and UFO Plant. I have numerous tries on Bird of Paradise and none success. I have problem with Snapdragon and Dragon Fruit too. Before Seasons, there is no problem with that. I have tried maybe about more than 10 tried but always in same order that Snapdragon as base plant and Dragon Fruit splice in. Never one success, always only produce Snapdragon. Then I tried different order, Dragon Fruit as base and Snapdragon splice in. It's successfully in first try and I got Cowberry. So later I tried to splice in UFO plant to Dragon Fruit and it's successfully too. I haven't tried with Bird of Paradise cause I'm waiting for Dragon Fruit to be mature enough. I will come back again to inform the result.
So maybe you need to specify in your guide that Dragon Fruit need to be the base plant to successfully get Cowberry.