'Folk' is fine, though try to work out how to drop 'comrade' into your vocab.
In this particular case, the OP could have used 'researchers' and: 1. avoided putting off/distracting people by the use of gendered language; 2. been more precise.
Also a native speaker, here.
Seems to me that "guys" can refer to a group of men, or to a mixed-gender group, but not to a group of women. So while it's absolutely the case that it can refer to a mixed-gender group, using it that way is still problematic in that it emphasizes men's membership.
Re:Why we should love null results
by lucasmullens on Sunday June 04, 2017 @06:34PM
(#14484027)
I use "guys" to refer to groups of women all the time. I don't think people who say "you guys" check and make sure it isn't 100% women before saying it.
Regarding GP, my only guess is that they were virtue signaling because they explicitly went out of their way to make that point. If they really wanted to avoid gendered nouns they could have written "folks", "people", or any number of similar words (kind of like how I'm doing here, by not assuming GP's gender).