I've seen a few sources call Reisetomate Brain. The name has apparently possibly been circulating since
at least 2009 (probably before). See post #6 in that link. It's possible they were referring to another variety as Brain, though (that's how it looks, but it's in the same sentence as Reisetomate as if they are tomatoes with similarities).
One person got their 'Brain' tomatoes from a French source.
Another got their tomatoes from a Croatian source. In this case, Brain was a translated name and the seller called it "rajčica mozak".
Here's another site that refers to it as the Croatian Brain name.
Then there's this
eBay source, which is Croatian. And there's this
YouTube video.
And this foreign language website.
Since I brought it up, in post #29, though, where I first saw it called Brain, with the heavier weight advertised that I mentioned in a different post, was
here.
Anyway, I'm not saying we should say Brain is another official name for it, but it does appear sometimes to be called that, for whatever reason. It is a pretty rare name for it, though, it seems.