After few updated I tried to play this game again and still I hold my opinion that developer has great ideas but executes them really bad. Fighting system got better but skills upgrade system is probably the worst I've ever seen. Why upgraded skills are worse then non upgraded (i.e. first skill of catgril is usable always, after upgrade it requires almost maxed rage)? What worse there is no information on the UI that this will happen. Inventor screen is really bad with no possibility to sort items. When you use up all your potions new one will appear on the bottom forcing you to scroll through list of junk to get there. Crafting system applied over this list is annoying when you need to highlight one item and see if others were highlighted scrolling up and down.
I'll wait for few more releases before playing again. I prefer Japanese dungeon crawlers like Bunny Black or Rance IV where you fight often but battles can be speed up so they are brief so you mostly focus on building your team, not button mashing during battle.
The Bunny Black series is definitely the best hentai dungeon crawling games out there at the moment. The problems surrounding the translation of the third game, have been solved. Now there's even an interface patch to help with the info of the buildings etc. Clearing Bunny Black 3 with the info from the japanese wiki and google translate is also entirely possible, but very tedious... that's how I got through my first time. Allegedly, translation of the game have begun. This will probably take a long time before it's complete, but at least it's a start.
I agree with some of your critique, but not entirely on the upgrade system. You just have to keep the requirement in mind and only focus down one of the upgrade paths.
The retardation in this system is truly, that attacking increases focus (decreases rage). You'll not be able to attack on your first round and then use the more powerful attack ability the next round. The way I worked around this against stronger enemies, was using lewd odor on the first round with all my mons. Stunning all the enemies for approximately 3 rounds. Debuffing and buffing the next round and then attack. Against weaker enemies or one strong enemy with weaker ones, I'll use the method mentioned in my earlier post. Another thing I dislike, is that you kind of have to choose which mon gets the abilities of the boss enemy. Being able to refight or ask the new mon nicely, after it have been calmed down. Letting the other ones learn the abilities, would be preferable.