Basically I don't think otherkin or transracial identities are related to being transgender.

I wrote more extensively on my thoughts on otherkin identities in this comment.

I wrote more about transracial identities in this comment.

And in general, it is a good idea to respect people's self-identity even if you feel skepticism about its validity - I don't have to know someone has 100% figured themselves out and has the self-awareness to back up their identity claims. This goes for cis people as well as trans people. Whatever skepticism I feel can remain private so I don't cause that person any distress, and so I remain polite and respectful.

I do believe non-binary, gender-fluid, and agender people are natural variations and are "valid" as much as binary-gendered people, the science and evidence does not really contradict these identities and only seems to affirm their existence.

In cases of the neo-Nazi who identified as a woman, I know this is a major controversy but if there are reasons to believe they are earnest in their identity it should be respected, even if they are despicable. How we know if someone is being earnest is harder, it's a way trolls exploit this respect of self-identity. So we look at a troll's other behavior to help us gauge, and we judge them for their other behavior, not their identity.