I have to say, the game is far too grindy for my tastes. The player needs to repeat a lot of actions in order to have any chance of finding rare treasure or reaching the next event or so on, even with the fully upgraded treasure finding item and the bonus experience for consecutive fights. It's a little frustrating for the fun wardrobe options to be gated behind rare items, for example.
I see that Nel can do the grind for you, but whenever she's in control you're asking the player to stop playing the game, which doesn't really address the issue. (She also doesn't tend to find the good items or level up particularly quickly.) If the player needs to do a lot of fights themselves in order to get these things, some options to reduce the amount of time for combat animations or treasure-finding animations would be helpful.
Combats are generally always about the same within each area, which adds to the grinding feeling. For example, along the beach, the combat is always against exactly one jellyfish. Could it make sense to occasionally vary the number of enemies per area, or to add some enemies from earlier areas occasionally? Older enemies could be recolored and brought to a higher level to add variety without needing to create a whole new set of animations. It might feel cheap, but it would add variety in which elements to use and how to plan around a different set of opponents.
The art is extremely well done, and it's clear that there's a lot of effort put into the whole scope of the game, but it feels like it'll take an incredible amount of time to see the whole game. But, I must admit, I am approaching this as someone who wants to see the content more than enjoying individual fights. I might be in the minority.