As far as the leveling system goes, it just feels... well, it feels equal parts exploitable and obnoxious, I guess? Like, don't get me wrong, it's a creative idea to use items as a resource for leveling up, but I feel like giving Vacdes "trinkets" shouldn't be the ONLY means of leveling up.
Basically, I feel like the system is exploitable in the sense that someone with enough patience could just stick to the first few areas to collect trinkets (flowers, sea shells, etc.) to trade Vacdes and end up at a crazy-high level before they even complete the first real quest. On the other hand, I feel like the leveling system is obnoxious in the sense that combat has no real benefit to the player outside of getting sex scenes and grinding for a few types of trinkets to trade Vacdes; essentially, there isn't any huge incentive for the player to really pursue combat.
I think incorporating an experience points system into the mix could really improve these aspects. That isn't to say that I feel the current leveling system needs to be removed or anything; far from it! I think there's a way to combine these systems into something very unique and innovative!
Like, what if, to level up, a character needed to trade Vacdes enough "material" to reach the next level and a "catalyst" to actually execute the process? "Material" could be made up of experience points (earned by defeating enemies, completing quests, etc.) and/or trinkets, where a trinket with a trade value of 1 is equivalent to having an additional 10 experience points, and the "catalyst" could be any trinket(s) with a trade value of 1 or maybe even a trade value equal to the character's current level or something. For example, lets say a level 1 character needs to provide at least 150 experience points worth of material to reach level 2, not including the catalyst; in this example, the character needs to provide any combination of experience points and trinkets with a total value of at least 150 experience points (15 trade value) as material, so they could just defeat enemies and complete quests to collect the needed 150 experience points, collect trinkets with a total trade value of 15 or more, or some combination of the two to collect enough material to level up.
This is all just an example, by the way; I'm not saying that this is the only way to do this. All I'm really saying is that the leveling system should, in my opinion, be modified so that there's some incentive for the player to defeat enemies and complete quests, outside of hoarding trinkets and getting sex scenes.
Just food for thought; you do you with this game and take it where you want it to go. If you like this idea, feel free to nab it for the game, I don't mind; if you don't, well, there are plenty of other options for fine-tuning the leveling system, so just keep my critique in mind, I guess. This is your game, after all, and only you really know what your vision is for it's completion; all I want is to see this project reach the maximum potential I know it has! If you want clarification on anything I said here, all you gotta do is ask and I'll explain it as best I can!
(Don't worry about the late reply! I know as well as anyone that life just gets in the way sometimes. Not like you can spend all your time waiting for and replying to comments on itch.io, right?)