My son's school is AMI accredited and at least there's not much woo-woo here. Children have to be up to date with vaccination (or they're not admitted), only thing slightly woo-woo (from the local point of view) is that the parents who chose this school chose it because they want their kid to have more of a play-based, child directed education and don't want them to have homework and tuition in kindergarten. This is in HK where a lot of children going to public schools will have homework and will get tuition in order to prepare for the primary school entrance exam (and later to the middle school entrance exam).
On the other hand, Waldorf is fully woo-woo. They claim that children should not be taught to read before they get their first adult teeth and have a bunch of very weird racist myth about reincarnation (read up on anthroposophy)