I figured since isn't much out there on this game right now. I would point out two things I've noticed that might be helpful.

The boss on town 7 can have his fireball cancelled if hit at a certain time. I would guess it to be around 2 or 3 frames near the beginning of the attack. This will lock him in the animation of the attack but not produce the hitbox of the fireball. It will need more testing to nail down the timing.

The witch in town 8 can not hit the player if they stand very close. The fire arrow will spawn behind the player and allow her to be hit. Even if the window is missed, running into her deals less damage than being hit by her arrow, making it fairly low risk.