Too early in development for voices, other than maybe some pitch-shifted grunts and little moans.
Real big problem with a lot of in-dev games, especially lewd ones, is that devs rush to get the good art and the good audio, but then something in the game changes and they have to toss what they've got.
>commission an artist to do your character art; a year later, you need more art, but the artist is busy or their style changed
>commission a VA to voice someone; a year later you need them for more lines, but they can't/don't do the voice anymore, or they got popular and raised their rates, or they're too busy
>pay for art for a character, then later decide the character should look different, or you delete the character entirely, or you decide to change the art style of the game
>pay for a voice, then later decide they should have an accent or a lisp or something
>commission someone, but you work faster than they do, so there's always a bunch of missing content that they haven't made yet
Watched a few different games run into major issues stemming from buying the good stuff too early, one game even collapsed entirely because their main artist got popular off working on the game and was too busy to do the game's art and the dev threw a tantrum over it after a few months of stalled updates waiting on the artist to open up.