As I know,
double-byte character set has been supported by "foo_http_sjis_patch2.dll" until foobar version 1.3.x
I checked it by testing.
foobar 1.3.x without foo_http_sjis_patch2.dll : dynamic title/artist were broken for double-byte character
foobar 1.3.x with foo_http_sjis_patch2.dll : double-byte characters are shown normally.
But, from foobar 1.4 beta, it looks like that foo_http_sjis_patch2.dll doesn't work.
I think that it would be better if 'double-byte character support for online streaming' is implemented into the future foobar itself. Would it be possible?
foo_http_sjis_patch2.dl : https://foobar2000.xrea.jp/up/files/up1052.zip
Double-byte test streaming : http://www.mukulcast.com:80/
The online streaming dynamic titles are only available in a few formats:
MP3/AAC: Shoutcast tags. Limited to ANSI encoding, probably coded to only support ASCII.
Ogg container: Chained streams, using one full UTF-8 tag per stream.
Matroska/WebM container: Probably something for this, not sure.