I can say with confidence that “if” there is an issue in tinyG FW, it will be corrected in a version later that 438.02 (current edge), so yes, you might as well go there first.
Not much experience or knowledge of rotational parameters here, so A settings are hard to comment on without a lot of research. $atm = -1deg looks a bit strange, but of course why would that affect G2 and not G1 moves.
More and more folks headed down this path, let us know how you make out.