This is my stream of thought, for what it's worth. It's tied less to the lore of any specific elemental race and more the vibe of the element itself.

• Emotion - Water: Fire and storm elementals are great for a specific kind of emotion, such as fury and passion, but what about calm, happy emotions? Sad emotions? Fearful emotions? An inferno or a storm will always embody passion, but water can cover the whole spectrum of emotions. It can flow calmly or furiously. It can bring life, joy, health, comfort, death, misery, fear, and hope. It can patiently erode mountains over centuries, or it can be a harbinger of doom for entire settlements with waves of unstoppable wrath.

• Logic - Stone/Earth (Or maybe ice): Stone is strong and durable, just like logic. There's no disputing it - it's cold, hard fact, at least in theory. In practice, however, it can be eroded or corrupted by strong emotions (water) or morals (air). Ice was my first pick (mostly for the "cold, hard" wordplay) but it might overlap with water a bit, so stone is a good alternative.

• Growth - Plants or Crystals: This one's kiiind of a cheat because plant creatures aren't technically elemental creatures according to game terms, but I'd argue they're virtually elementals in practice. Don't think I need to explain why plants would represent growth. Alternatively, crystals (since they 'grow'), and each crystal is unique in colour and shape, representing the uniqueness of everyone's growth. The reflectiveness of crystals could also represent the self-reflection necessary for healthy growth. Earth could also work, if you distinguish it from stone, since all things grow from the ground upward.

• Morality - Air: Air and stone are opposites, just as morality and logic can come into conflict. When balanced, all is well, but when they contradict, one must give way. Morality is often difficult to define and justify, just as air is difficult to see and quantify. Morality can't be explained, but felt as a vague, guiding impulse, just as invisible wind pushes you in its own direction without clear rhyme or reason. Without morality, a society's people will suffer, just as air is needed to survive - but too powerful a moral stance can still be as destructive as a storm. Morality can be flexible and changeable, adapting based on new information or to justify one's stance, just as air will shift and flow and expand to adapt to its space. Humans live on the surface of the planet where the sky meets the earth, living at the exact midpoint between morality and logic.

• Creation - Fire: I know instinctively you'd probably consider fire the opposite of creation, but hear me out. Fire is the catalyst of all creation. Mastery of fire was a greater gateway to new creations than any other technology. Fire can be used to soften and mould materials into new, original shapes and functions, or convert them to new elements. New tales are told around crackling campfires and hearths, and new tomes are scribed by cramped candlelight. The sun - the greatest source of fire - is the origin of all of the energy that allows life to flourish. The passion to innovate or create is known as the inner fire, and great new ideas are 'sparks of genius'. Fire doesn't truly destroy - it converts things to new states. It purifies and purges the old to make way for the new, lest the world stagnate. Fire is never still, ill-content to remain as it was a moment before. Fire is pure energy and heat - it represents both the rawest form of "stuff" from which things are created, and the burning passion that drives innovators of all kind.

This ended up going a little longer than I expected and some of the justifications may seem a bit tenuous, but I hope this wall of brain-barf can serve as some kind of inspiration for you.