No. Japanese game circles usually just do the same with more content, mechanics, etc. But "the core" of their games will always stay the same. That's sort of their "thing" and expectation of japanese players. Buying games from those circles means you always get what you expected.
If they want to do something different, they usually publish under another name, create sister circle, etc.
Most of this, I agree with. A circle normally focuses on one aspect of design and engine. But in Umai Neko’s case, they’ve already done that. If you would look at their catalogue of games, you would see that they’ve started with Fighting Girl Sakura. A very difficult side scrolling beat ‘em up. It has then evolved to Fighting Girl Mei which added a live 2D HCG upon giving up. And now we’re on Fighting Girl Sakura R with little improvement other than the art style which was a huge step up.
While Umai Neko was known for those games, they have deviated from it and made an actual beat ‘em up(Double Dragon, Streets of Rage, etc.) in the form of the Fairy Strikers games with Fairy Heart, Fairy Flower(the inferior one imo), and now Fairy Princess which is the pinnacle of their catalogue. And now Fighting Girl Yuri is following in its footsteps while keeping its Fighting Girl roots to the standard side scroller that they’re known well for.
So to say that they won’t do more content, mechanics, or whatever that they can change is not completely true. It’s just a matter of what can else can they do differently. Considering that they’ve been using Game Maker Studios as their game engine up to this point, they are only hindered by the limitations of the engine. Unless they try to deviate on the engine itself to make something new and unique, then the sky’s the limit.