Overall very fun experience! The animations are cute, the characters are... appealing, for lack of a more polite term, but gameplay does need some balancing. The player is very squishy overall and the effects of each team member feel very limited. I recommend some of these to help out, but only if you're open to feedback:
1. Try implementing mid bosses, it will give players more time to grind and maybe get used to some of the big bad's tactics. Before being thrown straight into the pits.
2. Items. A random health drop that gives 10-25% health back would be a lifesaver for players, Reigh's healing buff just isn't enough to cover actual healing when you are thrown headfirst into Cthulu.
3. Reconsider some of the roles each character plays and how they play them. I love the idea of switching mid-combat to whatever character you want, but the "buffs" each one supplies just feel watered down, which could have been an attempt on your part to make them more balanced, but I think they would be more enjoyable even if the player could just select one play style and lean into it more.
4. Passives and Gameflow. Taking from the last point, either the player just doesn't have enough time before hell breaks loose, or the character's abilities are too watered down for the sake of being novel. Don't be afraid to make each character more rigid in their role, Cedric is clearly supposed to be the early game grinder with the biggest range and exp boost, Bogart is supposed to have higher speed and a chance to crit, which is great for dps, and Reigh is supposed to tank having healing at the expense of range. You can totally lean into these more and make each character more enjoyable to play without taking from the overall experience.
If you got to this point, well thank you! Clearly it shows you have a desire to improve the game and I genuinely believe in your ability to make this a super fun experience across the board. Hopefully my feedback along with that of others can help you find the missing links to implement your ideas in an even better way. Keep up the awesome work! :D