Just had this same question again today (last time was 7+ years ago, wow!) and it looks like they don’t have this high up on their priority list, considering last reply in thread I linked above also:
Probably this means that in their own / big clients’ projects, they don’t use Child Actors in same way we are trying to. So maybe we’re using them ‘wrong’. I’ll see if I can think of alternative approaches for my use case at least.