Yeahnahyeah IMHO their are lots of different issues, not just young people/children (although for me this is probably the biggest issue) but for me I prefer not to mix up the various issues. Rather to stick with the thing being discussed.
In terms of suicide stats I think the issue here is that, although it is probably true that some suicide stats are inflated in some areas, any parent who is worried about their child taking their own life won't be reassured necessarily.
Suicide isn't mentioned in the post at all but does go with mental health issues sometimes of course.
We may want to correct misconceptions or whatever, the reality is we do not know which young person may or may not hurt themselves intentionally or unintentionally.
Fortunately, in the UK (where I am) we cannot access cross sex hormones before 16 very easily, if at all, (as far as I can see) and we cannot access surgery for children (as far as I know).
I think in the beginning (when the child asked us to use male name etc) I thought if I go along with the 'new' name and pronouns I will make it worse. I will make it real. I will make it less likely to stop/end.
After a lot of heartache on all sides I found that rather than going away the 'issue' became more pressing. I also realized that if the child ever had doubts about their new identity then I would be the last person they would talk to!
I started to use the new name, the pronouns and generally accepted that this was the situation with the child. Amazingly I felt a lot more peaceful about it. The child seemed happier (although they have a lot of other mental health issues) and it did feel the right thing to do.
Of course the future is an open book, and maybe this child will change their views/identify or whatever, that will be their choice.
Good luck OP, make up with your sis, she needs you.