I should add that in Texas if I was using the you as a plural, talking to more than one person, I would say, "When are y'all coming back?" because the second person plural we use in the Southern part of the United States is "y'all".

When are you coming back to Texas is perfect. It's what I would say living here in Texas. :D

I think both "when are you coming back to Texas" and "when will you come back to Texas? are good.