So as the title suggests, roaring flames does not apply any buff to shoulder charge, or any titan ability as it seems. They just updated it to make uncharged melees do solar damage now which I love but it sacrifices every solar ability and its ability to benefit from the buff. I think this is a bug, at least i hope it is. (Source: I tested on carl on nessus and got the exact same damage numbers for my shoulder charge with and without roaring flames x3)