I was also curious about this topic and lost interest because I was not able to find info on FCOM or FCTM. The plane I was flying before had "half bank" function when operating at high altitudes. Airbus do not mention anything about half bank. There's a mention about the g loads limits. Bank angle protection is there also. So I guess the FAC will not let you exceed the +2.5 to -1 g's when clean. How does the FAC calculates it? I don't know.