Korean patches had 404 links and were not available on archive.org.
Chinese patches led to dead torrents.
Portuguese and Vietnamese patches are still work in progress.

When quickly tested with: https://nyaa.iss.one/view/1302069
English works, but do not use the voice patches since the above release already includes that.
French works, but must use the Avec Voix (with audio) patch. Sans Voix (without audio) makes the game freeze.
Russian works, but must install and set the fonts as described in note.txt.
Spanish works.

Download links in case this torrent loses all seeders. The text below is taken from the note.txt files from the torrent.
English

http://radicalr.pestermom.com/vn.html
https://plsnohate.wordpress.com/visual-novel-hacking/ultimate-voice-patch-for-kanon/

#1 Kanon.7z
https://web.archive.org/web/20170905110152/http://radicalr.pestermom.com/patch/Kanon.7z

Warning! reallive-patch.exe is detected as Win.Trojan.B-365. Author’s response:
01/29/19 - It certainly has been a long time, my friends. If you are here to download my admittedly old patch, I have taken it down temporarily, so I can recreate the patch for the executable without tripping the anti-virus software. In the meantime, please check out this fantastic voice patch that puts our project to shame.

#2 Kanon Voice Patch.rar
https://drive.google.com/open?id=0B31Tf9j1VWKmVncyaGlBWmQySGc

#3 Voice Update 1.zip
https://drive.google.com/file/d/0B31Tf9j1VWKmbDFDS1NsTjU1bHM/view?usp=sharing

#4 18 patch.zip
https://drive.google.com/file/d/1bdzH4q5M-RICNv_wBDW_v_QuLyjauI6a/view?usp=sharing

French

http://zebdal.free.fr/whitedream/kanon.php

Avec Voix
http://zebdal.free.fr/whitedream/jeux/Kanon_Patch.zip

Sans Voix
http://zebdal.free.fr/whitedream/jeux/Kanon_Patch_Sans_Voix.zip

SEEN.TXT
http://zebdal.free.fr/whitedream/seen.rar

Si vous avez des bugs avec votre version (avec ou sans voix), veuillez télécharger ce fichier : seen.txt
Il vous suffira de remplacer le fichier existant dans le dossier du jeu par celui téléchargé.

Russian

http://enthusiasts-ts.ru/load/kanon/kanon_dlja_vsekh_vozrastov/2-1-0-16
https://yadi.sk/d/E7t6awDL8j2Ka

установить в windows эти шрифт: Kanon_Lucida.ttf и Kanon_moon.ttf.
использовать шрифт Kanon_Lucida.ttf или Kanon_moon.ttf в Канон (ЧИТАТЬ.bat).

Spanish

https://web.archive.org/web/20160323065042/http://blog.keysf.com/2016/01/KanonParcheCompleto.html
https://www.mediafire.com/file/55k9czy0u8vf3pa/%5BKeySF%5D_Kanon.exe/file