To start, I must apologise sincerely for my harshness. I tend to not mince words but that is no excuse for rudeness. I would like to still emphasize that your game is still very solid and I feel is the polish all games should strive for because I FEEL that quality and effort you put in.
Anyway to give a proper response, I rewatched my own VOD to regather my thoughts.
I think the bug might be entirely the demo so I feel that I could disregard that money and sound but entirely. An oversight? maybe a build issue but regardless, its nothing a bit of debugging can't fix.
Now to the crux of it. For the controls, I recommend you do away with the WASD + Arrow keys and instead opt for WASD being the control, space bar to jump and the mouse as the key "attack" function. Left click to shoot and such. Maybe map some other buttons to do other things that are convenient like Q and R. I feel that this would do your game a lot more justice since you can just use the mouse to click during the RPG section, to attack during most of the games and such. However, I understand it'll be an insane programming feat and if you feel its better to stick to WASD as the interaction buttons and the Arrows and movement, I recommend the ability to remap it. I think this could mitigate a lot of issues but I feel like its not gonna do much cuz I feel that games like these should be simple-ish and let me get right to it. Alternatively maybe you could also had a huge "Play with Keyboard or Gamepad" option. As mentioned, I feel that would be a good indicator, I could easily get my XBox controller to play. Still something to consider.
As for the RPG section being clunky. I gave it a lot of thought as to why and how to fix it. The why is a bit vague but it feels like an old FF game interface or something you'd see from an RPG maker game. Feels classic. However, I looked back at it and functionally it was perfect, I even praised it for being perfect. I feel that the issue was the pace change. You started off with a Bullet Hell, then to a Rogue Shooter, then if I picked the other side, a Platformer, so to change the pace to RPG... it would slow down and make the experience clunky. My solution to this, is fairly simple. Give the main character, AOE spells right off the bat and have MP be refilled per hit rather than through potions. Small changes BUT I feel that this would speed up the RPG sections without making it too easy. Consider this, that each monster requires 2 to 3 hits to kill, You drop anywhere between 2 to 3 monsters and that means 6 hits in total if its the best case and 9 to maybe more hits at worst. So an AOE spell that early helps. I also saw the trailer and guess that, maybe, the companion girl would be the AOE spell caster? I might be wrong but still waiting to that point, might be too late to establish a pace and my mind just went from "gotta go fast" to "I've just been glued to the floor"
Overall I think that if you do that for the RPG section it might keep the pacing consistent enough that no one gets taken out of the game while playing. Make the blaster or sword AOE and maybe add a super strong attack spell for all the marbles. I made a comment about how there should be one major element to the game despite there being multiple genres. I think keeping a somewhat consistent pacing between genre changes is the key to solving your problems. I mentioned No More Heroes: Travis Strikes Back as a good reference. So maybe something there can help you.
I still love the look of the game, its concept, the characters. Its a good game with polish but I feel like its bogged down by some fundamental flaws that I feel could be mitigated if not outright fixed entirely.
Please keep up the good work and I hope to play your game again ^^ and I apologise once more for the harsh critique.