I think Lauda is hanging around, but I don't think she is Ratimov. Really hard to believe she left the forum for good without any real good reason IMO.
I'm almost certain Lauda is a "he", because Theymos referred to Lauda as such one time, though that's making the assumption that Theymos knew enough about Lauda to know that particular fact. But since Lauda was so private, even about gender, I usually tiptoed around it when referring to him/her. Do you happen to have the scoop on that?
While writing in Croatian, Lauda always uses masculine gender. Croatian grammar is way more complex than English and it is quite hard to use gender other than your own, without slipping occasionally. Some time ago I shared few examples from Lauda's writing in Croatian, and how would it look like if he considered himself female.
All those that understand Croatian/Serbian shouldn't have any doubt whether Lauda is a male or female. Among other things, we have genders for verbs in past tense and adjectives. In his posts made in Croatian board, Lauda always used masculine gender. I remember some time ago I was so bored that I actually tried to find posts where he used feminine gender, to no avail.
Just an example from one of his posts. Adjectives and verbs are bolded, all masculine gender.
Razumio sam sada.
Ne bih
rekao ali u svakom slucaju ne bih ti
preporucio.
Da nisam
procitao ovu temu ne bih ni
skontao .
Zauzet sam nesto trenutno, ali bar ima srece s ovom cijenom.

This is how it would look like if it was written using feminine gender
Razumila/Razumjela sam sada.
Ne bih
rekla ali u svakom slucaju ne bih ti
preporucila.
Da nisam
procitala ovu temu ne bih ni
skontala .
Zauzeta sam nesto trenutno, ali bar ima srece s ovom cijenom.

Lauda's English was impeccable, by the way. I always thought he was a native English speaker, though for some reason I also thought he didn't live in the US or UK.
And that's another reason why OP is completely off, as there is a huge difference in English level between Lauda and Ratimov.