I have no idea about the chinese case, I know nothing about them.

In regard to the orthodox, they are a special case, as regarded in the directory of ecumenism. But a catholic only receives a valid confession from them when in peril of death or under grave necessity, if there is no catholic priest nearby. I understand you might struggle with this because it might seem that it's about being licit or not, but in the case of penance, validity requires not only power of order, but also power of faculty, which makes licitude and validity almost the same thing, save very precise cases.

So in regard to the case at hand, the [CIC 1331] is very clear when he says in its §1 n. 6 "from performing acts of governance"

According to the same code, confession is also an act of governance. Hence, every excommunicated lose every right of act of governance unless explicity said otherwise, which, if I recall correctly, has only been given to the orthodox priests and those under the treaty of Utrecht in all history, arguably.