The latest version of the Collabora Online Development Edition Docker image at the time of writing defaults to German language. This manifests as unexpected behaviour for English language input in new Collabora Online documents, such as quotation marks appearing inverted:
Fixing this involves changing the default language of the underlying ODF template files. In this example we’re using Collabora Online in a Nextcloud 12 host, running in Ubuntu 16.04:
1. Locate the ODF templates at /var/www/html/nextcloud/core/templates/filetemplates
2. Copy the templates to another system with LibreOffice loaded. Open them in LibreOffice (there are three files in ODF, ODS, and ODP format) and update the language to the English variant of your choice (for example English (New Zealand).
3. Copy them back to the Nextcloud host. Restart Apache and the Collabora Online Docker container, and confirm that new documents have the expected behaviour.