OP: Dude, you're
really obsessive-compulsive.
I'm kinda obsessive-compulsive, an annoying nit-picker, and serious perfectionist, and even
I'm not quite that obsessive-compulsive.
So, uh, I guess my response would be: you're not alone, but you definitely have a stronger compulsive need for equipotence or somesuch, than most folks. It makes me curious though why you haven't felt a need to make an equivalence/opposite to the True Neutral alignment?
Also: Where exactly do I go to make supplications, oh Lord of nitpicking?
I've done some of the same stuff to balance the scales, but I've never seen any need to make any equivalences to fifth wheels, third wheels, or the like, nor any need to balance out the numbers/potency of each side in the planar conflicts. If every faction was in constant balance, then what purpose would the Rilmani serve? Only seems right and interesting for the balance to be a bit skewed from time to time, as opposing forces try to recoup their losses or sabotage the current king of the hill.
Psionics is more the third point of the triangle of Arcane and Divine power, a triumvirate of mystical forces, or rather, means of harnessing power in a D&D world. True Neutrality is the ninth point and hub of the alignments, not really needing an equivalent, as all the others converge on it, like the peak of a many-sided pyramid or whatnot. While different factions have greater or lesser numbers amongst their populace and leadership, they also have differing power levels and organization that kinda balance things out (there has to be way more Demon Princes than there are Lords of the Nine, they just don't work together much so they don't overpower the more-coordinated, and likely more-individually-powerful, Ba'atorian archdevils).
BTW: the lawful planetouched race is the
Zenythri, from Monster Manual II, not Axani. Chaonds are, as you mention, their chaotic equivalent in the MM2. Chaonds have some slaadi mixture in them somehow, while Zenythri are descended from an unknown lawful outsider race (I would assume it's one of the one or two kinds that early Modrons or others exterminated; it seems implied that Zenythri only remain due to breeding amongst themselves, not any further interactions between mortals and their lawful-outsider ancestors).
Personally, I converted Aasimar, Chaonds, Feytouched, Tieflings, and Zenythri into ECL+1 templates. Then made half-outsider equivalents to the Half-Fiend and Half-Celestial, in the form of Half-Anarchials and Half-Axions (I just personally use the terms Axion and Anarchial to refer to lawful/chaotic outsiders in general, since there's no official term for either as far as I know; I derived Axion from the Axiomatic template in Manual of the Planes, which is the equivalent to Celestial/Fiendish, and Anarchial from the Anarchic template in Manual of the Planes, likewise). I prefer the sound of Axion to Axiom, and anyway, Axiom is an actual noun so I'd rather not use it as a species descriptor.
Feytouched and Half-Fey have always been, in my mind, the Neutral equivalents to Aasimar/Half-Celestial creatures, BTW. The fey encompass all (or at least many) alignments altogether, and are bound to nature, which is sort of the central force that makes the extreme alignments coexist and mix together in mortal realms. For whatever reason, I never really thought to bother with any True Neutral equivalents to the Half-Fiends/Tieflings/Fiendish creatures, etc.