I just discovered that Sound Juicer does do ID3 tags. You just need to have audio/x-raw-int,rate=44100,channels=2 ! lame name=enc bitrate=160 ! id3v2mux in the settings. I was missing the id3v2mux bit in my settings.
I still can’t add the year to the data though.
Update: EasyTAG doesn’t recognise the Sound Juicer encoded tags so if I got to add just the year to the files I have to add everything else as well. 🙁