It's indeed not trained on Becca and a few other characters. Some characters didn't have their art uploaded and had a very low amount of images.Is it possible that the Lora isn't trained to generate pictures with Becca? Somehow I never get something that it least looks a litte blt like her.
I'll train a new one when the tech update gets released.
Besides, you guys can try creating your own, it's very easy in civitai.