Other localization related packages includes:
### Note: Whonix doesn't include libreoffice by default
# libreoffice-l10n-ar
# libreoffice-l10n-de
# libreoffice-l10n-es
# libreoffice-l10n-fa
# libreoffice-l10n-fr
# libreoffice-l10n-it
# libreoffice-l10n-pt
# libreoffice-l10n-ru
# libreoffice-l10n-vi
# libreoffice-l10n-zh-cn
# thunderbird
thunderbird
thunderbird-l10n-all
### Input methods
ibus-gtk
ibus-gtk3
ibus-qt4
## Chinese
ibus-pinyin
## Japanese
ibus-anthy
## Korean
ibus-hangul
## Vietnamese
ibus-unikey
### l10n, i18n
## precompiled locales
locales-all
## arabic fonts
fonts-kacst
fonts-farsiweb
## chinese fonts
## Note: Chinese fonts look nice in Debian 9 by default, I (iry) am not sure if extra packages are needed.
xfonts-intl-chinese
fonts-arphic-ukai
fonts-arphic-uming
fonts-wqy-microhei
fonts-wqy-zenhei
## Hebrew support
culmus
libfribidi0
## indic fonts
fonts-indic
## Khmer language, used in Cambodia
fonts-khmeros
## Korean fonts
fonts-unfonts-core
## Lao fonts
fonts-lao
## russian fonts
xfonts-bolkhov-koi8r-75dpi
xfonts-bolkhov-koi8r-misc
xfonts-cronyx-koi8r-100dpi
## Sinhala fonts
fonts-lklug-sinhala
## Thai fonts
fonts-thai-tlwg