Unfortunately there’s no real way to make a background image behave nicely on mobile.
That’s why background images are usually patterns, or images which can be cut off without losing the purpose.
In your case, I would make the text a separate layer, and set it on top of the background image as a regular image element.
This would make it view-able on all devices, even as the right side of the background image disappeared.
Let me know if that makes sense or not 🙂