Do the devs read this at all? If they do, I have a couple of suggestions that might make the game for enjoyable. I would have found it more enjoyable if we didn't know right away what species the girls were (except maybe Esther since the MC has known her all his life), and to discover that along the way (like finding out Naira is a water nymph during her scene in the pool she partially transforms).
Also, if it's possible, can we choose what species our mother is and that would give us slightly different abilities/scenes with the girls. Like if we were half phoenix, our cum could have very slight healing ability (like Esther but less potent). I think this would make it much more interesting and add to replayability because we would get different scenes based on our magical ability. And this could be implemented during a Nefari scene (since she's studying a way to bring out our magical ability).
Whoa there, dude. Slow down. As exciting as your suggestion is, you're putting the simplicity of the game at risk.
For example, the reason the Dev already stated about showing what race they are is because the MC is literally living in a Manor filled with People slightly like him who has special traits (Kinda like the Xaviers School) so hiding who or what they are pretty much places barriers between the residents of the place. Sure, some of them might be slightly embarrassed of what they really are but knowing what they are makes it simpler in tolerating or rather understanding other's unusual behaviors (such like Velle's sexual tendencies and how she spreads it to the other residents).
As for the species of the Mother, it places a lot of additional factors of how the MC acts making the game slightly more complicated and with that at hand, having the players decide what powers they have will make the game larger and will take it longer to develop because the Developer will need additional time making new scripts, new scenes, and new ways to do new scenes for each power.
Some people here like this game because of its simple yet rewarding approach. Its also very straight forward but in a good way.
Adding those new stuff will also probably make the dev quit it trying to reach each deadline. A lot of devs these day takes whole lot of chunks only to abandon their games. We've all have seen our fair share of good games getting abandoned, I don't want that to happen to this game.