I'm curious, do you think all bias motivated crimes are trivial or just gender-specific ones? Vandalizing a female's car by writing b is gender specific against women, just as would writing the n word is racial and writing f is homophobic.
OP - unlike some here, I wouldn't be afraid of calling the police for what appears to be an escalating situation with your neighbors. At least get something reported and the police can tell you how to proceed. It sounds like they are freaks. Maybe the people telling you not to report are your neighbors