I'm NB/trans myself! Rethe takes place in a world with a somewhat different understanding of gender (there are two gender roles, but biology is considered a suggestion of which role you should take, not to determine it, and they don't even care too much about that), so it gets a little complicated.
The main character does a feminine job, but still is kind of attached to a masculine identity, partially because some of the concepts fit him better, and partially because IDing male lets him dodge an inheritance.
Seph is too tired to care about gender in any world.
Vedya is intersex, but IDs as female while doing a masculine job.
If I had to give them western labels, Rous is a feminine dude Seph is nonbinary, and Vedya is an intersex butch lesbian, but in world they all kind of fall into a nebulous "dangit, you aren't gendering right for your career path kids".
So... it's complicated, but I would safety say there is probably at least one lead character who you would count as trans by some definition