Why might some pages have encoding problems?

Question

CMS

I am translating Chinese CMS wecenter 3.0 from Chinese into Russian. The encoding is UTF-8 everywhere (both in the database and the pages are all encoded with it, and are indicated in the math tag), despite this, some pages are displayed correctly, but on others, and most of them, instead of Russian words, are krakosbras like: €–deє
If translated into English, then all all texts are displayed correctly. Problems only with Russian characters, despite UTF-8.