Objectively, the word “futunari” is widely used as a genre that includes characters with a female figure and only a male sex organ.
As such, it is a common label, regardless of how the word is translated from Japanese.
And if hentai content creators widely use the word in this sense, then we see no reason to do otherwise, and confuse players who are already used to it from other games/comics/videos. Exactly because we want to give people who like this type of dick-only character a chance to find our game quickly and easily.
And by the tag “newhalf” you mentioned, there are exactly 6 games on Itch. Six, against hudrends if not thouthands with tag "futanari". So almost no one would even guess to search for our game by that tag.
So we're sorry if it's difficult for you to find content that matches your preferences, but the objective reality is that almost all creators use “futunari” to refer to dick-only characters. And almost all players use term "futanari" and not "newhalf" to search for content with dick-only characters. And therefore, we don't see the point of departing from the common designation for the sake of the academic term of the word.