[Klashikari]

It seems you didn't understand well the issue in my first reasoning

Spoiler for reasoning:

The problem is that in the red text, Beatrice used "human".
As result, she can say there isn't more than 18 human on the island, yet allow the existance of "non human" (be it witches, animal whatever) on the island doing the crimes etc.
I don't see much contradiction as she didn't say herself that she is "dead" so can do all the things. She even repeated a lot of time she is "a spirit per se" and only get released from her cage of flesh. She even says that she didn't commit suicide, despite it should be the case.
Therefore, I don't think we can count Beatrice as a X that is dead and evades the "count".
Basically she cannot be part of the number of people counted, because of the assumption she is not human. She insisted on the "human" portion of the red text, so it allows anything non human, eve thousand of them, as long as there aren't any more people than the current 18

by contrast, when beato mentioned the first 6, she again used "人", which is was part of the 18 people red text. Therefore, they do count, especially if you consider the almight red text sword Eva-beatrice uses in the end