Which AI can edit these photos?

Then you've still got the colors to play with. A flyer for handmade pottery could lean into earthy reds and warm yellows. You can use Flux for image-to-image editing here https://yesai.su/en/flux . Describe the background colors you want and tell it to keep the bowls' shapes and glaze patterns. Save a couple of versions so your sister can see how each one works with the flyer lettering.