The way i see it, it is not that the shards are hitting 3 times each. With the fox attribute, PP gets a lot more range and extra fire damage (which is an extra line of damage by itself, same for Gravity Pole).
So, the 3 lines of damage you see each mob suffering are one for fireball shard, one for PP and one for extra PP fire damage.
PP and GP already become pretty good with the first fox attribute, with no downsides but the extra SP increase.
Taking the extra firebal hits attribute seems very bad for any PyroKino, imo. The effect itself is no where near good enough to justify the duration reduction, and on top of that you don’t get to use it properly for PP/GP.