I kinda love Rapappa's idea for all the hoverboard levels to have vocal rock songs! What if every song had a different character's voice actor singing it... Assuming in this hypothetical remake Lolo's voice actor is replaced, or they just have a soundalike singing for her song. You could both make the songs really silly (Tat nya-ing in the Jungle Slider vision, Popka singing because come on) or really emotionally climatic (Polonte could have Lolo singing sadly in the music, and when she rejoins Klonoa they could do a powerful duet ballad!) Also more vocal Klonoa songs would absolutely be a joy, whether in Phantomilian or Japanese~
They could honestly already do a lot of interesting things with existing mechanics, like the crystal fish that absorbs other enemies and the boomies. Although if they were already going to add more enemies with different powers, I kinda wish they added more to spice up the challenge and fun factor. Maybe you could use spring moos to bounce on other enemies and push you far upwards, like with the direction-changing arrows from the GBA games. Or fire shield-breaking spikes and missiles with the enemies that shoot projectiles at you. Perhaps have more enemies on screen like in DTP to keep you on your toes, and having more dreamlike platforms and puzzle elements like in Mira Mira but throughout the whole game. But yeah, I agree in that they should definitely do more interesting things with the 2.5D mechanics.
Speaking of which, storywise, I see what they were doing with having all the kingdoms isolated from each other, but it would be super fun to eventually see them all slowly reconnecting once the fifth bell is rang. Even reused levels could have more of a purpose if they show visible change in the world structure. I love the touch of the backgrounds having NPCs and even enemies in fun little scenarios that match the kingdom, like the Joilant mascot balancing on the ball you can hit, and Volk's citizens going through a freaking civil war while you're just hopping around. But what if as the game progressed the kingdoms started becoming more interwoven, and then you saw troops of Joilant workers trying to give cotton candy to violent citizens who use said cotton candy as sticky bazooka ammo. Or Volkians having an extreme snowball war outside of the Mira Miran Museum. Or Mira Mirans getting lost in the caves of La Lakoosha.
Or, like in DTP and how your actions in one kingdom directly affect the next kingdom, it'd be cool to see some sort of ecosystem being established between the Lunatean kingdoms, even before the Fifth Bell is rang. perhaps La Lakoosha provides healing magic and food that Joilant uses for magic shows and fireworks, and overpriced carnival food, respectively. Maybe Joilant sells explosives to Volk, and Volk citizens write autobiographies about the horrors they go through that end up in Mira Mira, where they're content reading about other people's experiences rather than having their own.
A Klonoa video essay also brought up how there are tons of parallels between Lolo and Leorina, which make me wish there were more moments of meaningful interaction between the two, maybe both their stances on being priestesses and their beliefs in the Goddess Claire. (which her presence could absolutely be more fleshed out as well, if characters mention her more and allude to more hints about her past, and how she could possibly relate to Klonoa as evident in the ending.) I also wish Klonoa had more agency as a character. He doesn't have to be as bubbly as in the first game, but I wish he asked more questions and was more invested in the world he's in. Or if he really is aloof and distant, that could be brought up by Lolo as she notices how he always feels so far off, delving into what little past he remembers, which could obviously be explored in Mira Mira~ I still want the mystery of King of Sorrow to be in tact, not too much revealed at once, but in Hyuponia the environment could have even more disturbing imagery about Klonoa's trauma and repressed memories and feelings, with visuals almost akin to Mira Mira's in terms of trippiness.
Maybe also have Popka and Lolo's relationship explored more, how Popka cares for her but shows it through scolding her.
Also, something I've always wanted to have ever since I heard of the rumors Klonoa would get remade, even before: Reorchestrated music with a mix of live instruments and stylized synthesizers from the 90s. Keeping the original spirit of the songs but giving them more of an edge, and that 90s video gamey feeling from DTP. Also the orchestral music would be, phenomenal if they were played by actual orchestras, especially Cursed Leorina, Ark Vr. 2, Mirage and King of Sorrow's Theme. Those dang strings man! I'll settle for a live orchestra..... to actually be released online cause there WERE Jagmo concerts with Klonoa songs but they were NEVER released on youtube dog gambit!
Anyways, in terms of graphics, PR did a pretty good job actually, maybe textures could be more polished, and, I reeaaally do not like that double chin Klonoa has now. It would actually be super cool if they had Sonic Team-level prerendered cutscenes for certain moments like DTP had, especially the Ringing of the Fifth Bell, Cursed Leorina, and ending scenes.
I kinda wish there was a fun cutscene for context of the memory doll bonus levels, like how Balue's Tower had a cute story. I wish you could also talk with Mommett more to learn more lore or even just to get to know him better, like the shops in Undertale. I also wish when you completed memory dolls you could actually somehow look through the memories the dolls captured in an unlockable short movie or mini-level, with lots of cryptic imagery and hints at different lives in Klonoa. Maybe not even just Lunatea...