There are no problems that I'm aware of as RA253MA is product of Rolled Alloys and 253MA is as name use in various codes and standards to identify the same material. The substitute A253MA should meet the same spec's ar the RA253MA material. They are covered under ASTM A240/ASME SA240
The reason for this that the composition of this alloy was patented and is/was made under license for the patent holder. Several major steel producers make the steel under various product names.
This material is one of a family of high temperature Austenitic Stainless Steels. The MA stand for Micro Alloyed, with rare earth elements to enhance the high temperature properties.