Alright, first off I'd ditch Summon Elemental entirely. Elementals are the spiritual fauna of Creation, the sort of creatures that run around in Miyazaki works as background noise. They're basically Pokemon, or the kind of crazy clearly-magical animals that populate mythology, like the firebird or a kelpie. Not sapient like raksha, or in positions of authority like gods, just... weird animals with elemental "magic". They're naturally material, and most of them probably don't have a dematerialize Charm. There's not really any call for them to be summoned and bound as servants.
So just make them background material underlying Sorcery, as a mechanism. You cast many spells by calling upon elementals. Spells like Calling the Wind's Kiss, or Dance of the Smoke Cobras, Raising the Earth's Bones, or Magma Kraken should all work through elementals. Flight of the Brilliant Raptor already explicitly conjures a temporary "savage fire elemental" to perform a suicide run at an enemy. Benediction of Archgenesis should effectively be an extended roll to increase the value of an area of land, performed by a workforce of spontaneous Wood Elementals. You could have an equivalent for repopulating the land with precious minerals, using Earth Elementals.
The thaumaturgical equivalent, for mortal occultists, would be knowledge of how to attract Wood Elementals to your crops, spreading fish guts around so that the bulbasaurs who come to eat them improve the harvest with their pollen. Or stopping forest fires by offering up a portion of the forest surrounding the fire as a burnt sacrifice to the rampaging charmanders, so they become full and sleepy. Or how to account for squirtles flooding the dam you set up to divert their river.
So, let's work off this to prototype a revised elemental species.
Mist Foxes
Born of Seasonal Fogs
Water Elemental
Mist foxes are one of the breeds of elemental most often glimpsed in much of Creation - but only glimpsed. They have the form of foxes made of condensed mist, and are born of the thick fogs that choke parts of Creation during certain months. They are particularly common around rivers, and so no small number of cities in Creation have mist foxes living wild within them, digging through steaming trash piles and extinguishing rudely-lit lamps. When a mist fox rubs up against a tree or a structure, it leaves some of its vaporous fur behind which lingers. As a result, as a mist fox patrols its territory it leaves a low-hanging veil behind it, which promotes the growth of greater fogs.
Mist foxes that endure such as the trickster-spirits that haunt Nexus (where they are known as fogses to the unlettered) or the guardians of the al-Ibli oasis learn swiftly to assume a human form. Indeed, they learn that trick before they become intelligent, and most foxes develop their minds through spying on and listening to travellers. From the front, the human shape of a mist fox appears to be a fair man or woman, but if viewed from behind they have a long misty tail and their head is hollow. The foxes enjoy the wails and moans of humans lost in fog, and seek to lure strangers away from their companions. There is no particular malice in this, but these water elementals find it hard to grasp things that only pose a threat to solid lifeforms. They might gesture to a lovelorn merchant from over the lip of a canyon and watch as he rushes over the edge, for mortals unlike mist foxes are unable to stand on low-lying clouds.
Most mist foxes never grow that powerful, for even the ones that survive the season of their birth wax and wane as the fogs swell and shrink. The sun burns off their strength and so they are nocturnal beasts, especially in the cities of Creation. Still, in the foggy rainforests of the East some mist foxes grow and grow, and as they become more puissant they grow more tails in accordance with the laws woven into Creation by Sima before the Incarna rose up and won their freedom. They may have six tails, and no more. The mightiest of mist foxes are fog banks that can envelop an entire town or wrap their tails around a valley. Foxes this large can no longer fit their entire self into a human form, so instead they weave a mannequin of dense fog and puppet it using one of their tails. It is said by some that there exists some mist foxes who have refined their control to such a fine level that they can sneak a tail down a man's throat and manipulate him as one might a child's toy.
Mist foxes have power over concealment, obfuscation and deception. Spells invoking them can be used to hide an army from onlookers, blind a man, or veil evidence of a crime. Contracts with more powerful ones might enable a sorcerer to control a man's deeds entirely. Mist foxes that an Exalt takes as a familiar feed upon her essence and gain more solidity and strength. The master of such a beast must be wary of the blame that they might attract, though, because the common folk know and fear the trickster ways of mist foxes and will assume that one who has a mist fox servant will share their familiar's nature.
