Getting a utf-8 board up and running

[AndrewD]

I'm having a certain amount of brain pain getting a full UTF-8 based language (Chinese) working, in order to debug some settings with my product. Would appreciate some help:

- Clean installation of VB
- Patched class-xml.php as per guidelines (function &parse($encoding = 'ISO-8859-1', $emptydata = true) => function &parse($encoding = 'UTF-8', $emptydata = true))
- Installed official simplified Chinese language pack (utf-8)
- Installed external product + its utf-8 language file (my own, as it happens)
- Imported database tables from the Chines site that reported a bug
- Database tables are all utf8_general_ci collation

There's three different behaviours showing up, see images:
- The main vb menus and text are being displayed as extended latin characters
- The imported product's menu text is being displayed correctly in simplified Chinese
- The imported product's database entries are being displayed as series of question marks
- Items added in Chinese to the forums are being displayed in a compbination of valid Chinese and garbage.

Everything in the database shows up correctly in Chinese using phpmyadmin, so I know the raw material is correct.

Any suggestions where should I start looking?