calligra-l10n-cs software package provides Czech (cs) localization files for Calligra, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install calligra-l10n-cs
calligra-l10n-cs is installed in your system.
Make ensure the calligra-l10n-cs package were installed using the commands given below,
$ sudo dpkg-query -l | grep calligra-l10n-cs *
You will get with calligra-l10n-cs package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Language packs |
| Package | calligra-l10n-cs |
| Version | 1:2.9.11-1 |
| Description | Czech (cs) localization files for Calligra |
| Sub Section | Localization |