In no particular order:
The towns needs to be differentiated; why can I purchase all upgrades and items from a little village at the very beginning?
The inn prices have too steep of a price increase, and there is no reason to not go to the first village and save 750N due to the previous point.
Items drops need to be modified slightly, and/or it needs to be made apparent what enemy drops what. I would suggest maybe putting a bestiary in the hunters lodge, it doesn't have to be detailed either (rocky armadillo has very THICK HIDE, etc).
Skill tooltips are useless; they provide basic information inferred from the skill names. For instance, I had NO idea that elemental abilities could cause status ailments until the castle at the end. I was even going to suggest removing elemental sphere abilities as they seemed pointless. Be concise, eg 'Elemental Sphere: Weak attack, chance of inflicting status', you could even remove the 'weak attack' part as the lower damage is observable over time.
Do the elements have any interplay? Certain weaknesses, strengths? Is that information easily available?
Be consistent with your bestiary and naming. Every enemy has a use, except the cats and the psychic squirrel at the start. I would suggest removing the cats, and having the squirrel drop the reinforcing powder rarely, or a very small amount of currency. Also, in that forest you had a warning sign 'beware of cats and dogs' when the actual enemies had different names.
The lost items quest did not update my reward money properly. I had to visit several towns before it was added to my balance.
I'm assuming void element has a chance to instantly kill? If so, you should update HP to zero instead of changing the 'is alive' marker. A character collapsed, on over 120 health, with no explanation as to why. Then when revived, the revive HP was added to the previous HP giving me 190 total, yet she was in a 'weakened' pose.
Graphically, you need a few changes.
There are no GUI indicators what to do in a smith shop.
Early levels are okay, but later (eg in the caves) it becomes rather bland and difficult to watch for any duration.
It is impossible to track the dust attacks, as the individual pixels are difficult to discern from the backgrounds. I suggest a cloud or smoke effect.
Enemy and party damage numbers are impossible to read in cave levels; white on goldenrod is not a good thing to do to your end users; maybe change the colour to red (a dark red, and darken the 'healing' green).
Maybe change the battle arenas to painted style backgrounds, similar to Final Fantasies, just to be more appealing. If you cannot do so, try to put a bit more colour/variety in them; add texture.
This is all I could pick up on before entering the castle proper.
Overall, a great effort, and clearly something you are passionate about. Just don't slump on the play-testing next time.