[Risolto] Taxonomy

Background of the issue:
I added Chinese to WPML, and it swapped one of the categories to Chinese, like it shifted a whole category from English to Chinese without translating any of the contained posts. You can see the issue on this page: link nascosto

Symptoms:
A category was shifted from English to Chinese without translating the contained posts.

Questions:
Why did adding Chinese to WPML cause a category to shift from English to Chinese?
How can I fix the category language issue without affecting the posts?