Thanks for reaching out. Fortunately, your account is not lost, even though it's a guest account. Unfortunately, our usual advice would be to reinstall. We are aware of this issue with the text not displaying correctly, but typically once you tap the light blue button on the right everything proceeds normally. If that's not happening, then I suggest contacting customer service with your account information at skullgirlsmobile.com/contact
They will likely ask for your Username and then some description of your account so they can verify that it's yours. From there they should be able to setup a temporary Email login for you.