Well, I don't really know much about being a ryouseirui but I know a few people who calls themselves ryouseirui or are being called by others ryouseirui.
You should just ask them directly via their ask.fm
Kumaor Kidomirikemawas a youtaite who sings as both male and female. But because of personal reasons, he changes his alias to Keira and __ (I don't remember) and finally, now, it's Kidomirikema. His ask.fm is still active, he check once in a while
Leon or fureliesI think Leon is a girl, if I'm not mistaken,, and Leon sounds like both Boy and girl. in the Connecting indonesian version chorus, Leon sounds like girl, but in unravel, I dunno//crais I'm not sure if Leon's ask.fm is still active or not,,,
Acron or AcroneeI think she (I remember I saw her selfie and Acron is girl,, except Acron is lying) is also being called ryouseirui. But she isn't sure herself (?) But her voice can sounds quite like a boy and at times, kinda like a girl.
I'm sorry but I can only think of those three people and two of them are probably girls that sounds like boy. Totally not sure with Kuma. Sorry I can't help. I can only give links to some people I can remember. and sorry I'm not experienced and knows nothing about ryoseirui training.
Some more random tips which has nothing to do with ryouseirui training is, well, get more youtaite friends. It's hard to 'be friends' with utaite because of language barrier and how we are 'fan'. Instead of just asking here, or some other forums, try make friends. be friends with your friends friends and eventually you might meet someone 'expirience' in the community. Sorry if you're already doing this.
Anyway, this is all I can give. Better than no reply, I guess? Hope you're fine with this kind of answer.