Anyway, can anyone make a coherent argument for why she should not be allowed to be present for her trial, or why her citizenship should be revoked?
Here's the argument I would make, if she had been an adult at the time: Pledging allegiance to some other regime that's at war with your country voids your right to citizenship in that country. If that other regime can't make it as a sovereign nation-state, that's your problem. If that regime loses the war without ever becoming sovereign, then you are stateless by your own hand. Your former country owes you nothing.
As a separate issue, stateless refugees from a failed regime are a humanitarian problem to be solved collectively by the nations that care to solve it. This would probably end up with a consensus agreement between those nations that refugees would be repatriated to their former homes, which would then deal with them according to rule of law. Such refugees could petition to be repatriated to somewhere else, but that would be entirely up to their desired home to decide whether to grant the petition.
With very few exceptions (none of which occur to me right now), none of these refugees should be tried in absentia for any alleged crimes. If you have the jurisdiction to put them on trial, you have the responsibility to bring them to trial.
However, in cases where the "foreign fighter" was a minor at the time of their absconding, the automatic loss of citizenship should be waived. A trial should be held (with the accused present), and if the accused recants their allegiance to the foreign regime, that should be the end of the citizenship question.
I see nothing in this particular scenario that makes me think I should reconsider. Does anyone else have anything that might change my mind? Or that I should at least give some serious thought?
ETA: One reason not to bring her home for trial just occurred to me.
