When using the ftp-upload, there is no support for the Scandinavian Letters (åäö)
This is not a 4.6-version-only problem but since it's possible to use the letters in ITPC why not in ftp-upload?!
Regarding the use of Scandinavian letters in folders etc in ftp-upload
First, international (non-ASCII) characters are a completely different thing in IPTC and in file (folder) names. But both depend on all sides to know what the character set is to display them correctly.
The problem most probably lies with the FTP server. In my experience, most FTP servers out there do not understand Unicode but just plain old 7-bit ASCII. Even FTP specification itself calls for ASCII only. While there are supplemental specifications for Unicode encoding of file names for FTP, not a lot of servers seem to accept them. From my very limited user-only testing, Photomechanic sends any accented characters in file and folder names as UTF8. At least on Mac OS X. But my website server I tried it on certainly didn't understand UTF8, expecting ASCII only. This of course created problems, as I could not even remove the test file - if I didn't know how to use \Escape codes I would be pretty stuck ;-)
The safest practice is to simply only ever use 7-bit ASCII filenames. Because you never know completely what the other side might be reading the files with. For captions, only use IPTC-XMP for international characters, again, because plain IPTC doesn't tell what character set is used, unlike XMP which has this support. Unfortunately, a lot of international newspapers are still stuck with old systems hand-coded for their specific character but supporting only old IPTC. But with file and folder names, still the safest is only ASCII. It will be a long time before internet becomes
internnational in this regard...