It's more like an intermission. I was thinking people are getting a little bit sick of Cecille.
Next update is more of Elena, but there will be a scene or two with Cecille. Depending on how much time I get.
You do you, but if you want my two cents if people were tired of Cecille they'd have stopped checking in long ago. Have some faith in your female lead (and she is your female lead by far and away just by the amount of time spent characterizing her, her screen time, the number of lewd scenes with her, the number of options the player has where they can choose to show her favour compared to the choices they can show favour to the other girls, etc).
If you wanted to add an intermission, I think Lavinia and Vi are starved for screen time and thus are the most obvious candidates, and Sera could stand to have a little more as well (even if I don't much care about her, she was an established character and is effectively Cecille's sister in this whole curse business). Another thing you could've chosen to do was add optional interactions during the content there already was, such as chats with Vi and Lavinia.
Optional content that helps build the world, lets the player favour one girl over the others and makes things a little less "railroaded". That also gives players a reason to go through the story again to experience the new content (assuming, of course, that there is enough of it, though judging by the scale of the last update that shouldn't be a concern) which is always a plus in such episodic narrative games where people might've gone through the starting chapters months ago and be forgetting some important details and most of the world building. It also gives players an opportunity to rethink which girls they want to show favour to without making them go through the entire game again solely for that purpose.
It's not that Elena is a bad character - I can see multiple comments from people who loved the latest update, and that's proof enough for me that you did a great job as usual, even if she isn't at all my type - but she and her corruption are a fairly radical shift of tone from the rest of the story.
I get that you want to characterize and play around with the new character you just introduced, but giving almost all of the screen time to her for two updates straight is a bit much. Often enough this is why sticking to just one or two female lead(s) is a good idea - because resources are finite and you have to choose one or at most two things as your goals and sacrifice all others in service of achieving them.
I'll be real with you, because 1. I liked the story until the last update, 2. I usually am not alone in these things, and 3. I reckon you could use hearing this feedback: I came here for Cecille (cover girl), stayed for Cecille (she had roughly 90% of all screen time before this update) though I really liked Vi and Lavinia and was willing to suffer through Sera's story to keep going, but with Elena you are starting to lose me.
But that's just my two cents. You do with 'em as you will.