Interesting game with a lot of unique mechanics! The way the party members are constantly changing state means that each encounter is different than the last even if it contains the same enemies. You're constantly on the edge of your resources, and unlike most RPGs where you can thoughtlessly heal every status condition, this one asks you to decide what you can heal now, what you can heal later when the Moon Beast or Jester transitions, and what you'll just have to accept.
The bosses are fairly short and easy, but by the time you reach them you're often so low on resource that it's still tense. I guess this is unsurprising given that this game takes inspiration from FF1. Oddly, I felt like the miniboss in the Tower was harder than the main bosses there, with the final boss being the easiest of the three. I fired off big spells at the ghost boss and the tower miniboss, generally playing the random encounters and other bosses more conservatively.
I feel like the way I routed the Cave and the Forest was fairly straightforward, with a fair number of resets when things didn't go to plan. I was able to line up a Full Moon Beast and get rid of Vencchio for the Forest boss by taking just a couple extra steps, so everything lined up nicely there. I usually saved my Mimic Stabilizers for the Vampire transformation since that made healing so much easier.
As for the Tower, I initially tried it without doing the Golden Bones sidequest, but I didn't have quite enough resources to make it work. I ended up deciding to look in the game files to figure out how to actually get the Mimic to take the form of the Golden Bones because the random chance of transforming into the Living Bones instead confused me. After getting the reward, I was able to brute-force the Tower with Sound Dampeners, which made it easy to conserve enough resources for the boss fights.