Unfortunately, Panharmonicon will not double the effects of kicker costs. Getting the boost from a kicker is not a triggered ability - an easy way to tell is the fact that a triggered ability will start with the words "when," "whenever" or "at" (as helpfully pointed out by Strionic Resonator.) Kicker is a static ability that functions while the spell with kicker is on the stack.
May 13, 2018 1:57 p.m.
In this case it is accurate, as the kicker effect of Baloth Gorger is a replacement effect that alters how it enters the battlefield. Panharmonicon will double effects of Kicker that start with "when," such as that of Caligo Skin-Witch.