When it comes to hentai games, I feel that the most important ingredient is personality. That means natural dialogue, aesthetics that fits together nicely, and music that can set the scene nicely.
Unfortunately, RPGMaker games have it rough on the aesthetic and musical front - they typically rely on stock assets without much editing to make them feel more unique. I recommend trying out the pitch setting on stock music and seeing how it changes the feel of any given piece. While certainly not as good when compared to original music, that is a relatively easy way to make things less generic.
Now as to reference games, that is bit of an issue. The first is that you seem to be going for a fairly standard RPGMaker game, some of my references have to be oriented around that. Further, a number of my favorites require an unofficial English translation patch for me to understand them, and the odds of them being in your language are less likely.
I will detail some of them, in no particular order.
#1: Monster Girl Dreams, on Itch.io. Freeware at the moment, unfinished.
A game based on the Ren'py engine, if I remember rightly. The strong point of this unfinished product is the dialogue and most of the art for the characters. While I do enjoy exploring the game and making out with the ladies, the actual gameplay doesn't feel good to me. There is a fair number of options for handling combat, but they don't really feel interesting to use.
#2: The Dungeon of Lulu Farea , official translation on DLSite. Unofficial patch for original version available.
While this game certainly has personality for the character interactions, the most defining aspect is the gameplay. You are tasked with conquering levels of a dungeon - but you have finite resources. To advance, you must carefully calculate the benefits spending your limited resources. I had to start a fresh campaign at least three times, but didn't mind much because I was learning how to optimize properly. This game is heavily inspired by the Tower of the Sorceror, an old Japanese freeware game from the 90's. There are some remakes of TOS on the Google Play store. DROD RPG also has similar gameplay. I really enjoy this gameplay, it is very different and thoughtful from the traditional JRPG grind.
#3: Naedoko's Demon Ground, requires an unofficial translation.
In this game, the gimmick is using pregnancy to birth a variety of monsters. Aside from being party members for combat, they sometimes are key to solving quests or problems. Somewhat hardcore, but a good balance of combat and dialogue. The dungeon design isn't good, but not awful either. I get the feeling that this game is the closest of the bunch to what you are going for.
There is actually quite a few hentai games worth checking out, and there seems to be a new generation cropping up on Itch.io and Gamejolt. These have potential, but are not yet finished and too numerous to go into detail. Shortlist: Haremon, Dandy Boy Adventures, A Town Uncovered, Monster Girl Island, and Third Crisis.
Not giving an opinion on your characters yet. I barely started the game, they deserve more time to leave an impression.