Parents’indulgence to their children is bad for them.有那里错吗？为什么？

以我的看法，指代有点混乱，后面的for them 和主语Parents’indulgence有点不对应，所以读起来比较别扭
表达习惯问题吧
可以试试这样表达
it' bad for the children to be treated with indulgence.
it's bad for the parents to treat their children with indulgence.

yes

Parents’indulgence to their children is bad for them.有那里错吗。 有点是从中文直接翻译过来的英文， 所谓中文式英文 Chinese style English.
应该是 用spoil 或 dot额＝过分溺爱才是

Parents’doting their children is bad for them.
Parents’spoiling their children is bad for them.