This is something I would like to look into, but it would require FTP access so that I can compare all the different encodings (input to the database, storage in the database, the connection used by vBulletin, the connection used by the importer, and what the importer decides when it tries to detect each of these). It looks like there was a problem somewhere, but unfortunately I will have to go line-by-line to find it, on an import where the problem occurs. Believe me I have done VW3 imports with Asian characters that came out just fine.
There are a few other issues I've noticed, such as some attachments have invalid description URLs that do not rebuild successfully. Also there was a problem where absolutely no default setting values were applied at installation (and this is the first time I've ever seen that).
By the URLs you've sent me, I am under the impression that this is was test import. Would it be safe to clear the VW4 wiki data so that I can see what happens as each item gets imported? I understand you must whitelist my IP through a firewall. I'm PMing that info to you now.