After CMS Setup is done docker-compose.yaml enter docker volume ls to see all the volumes created. There is one volume that has taxiassets in it. It is usually root_taxiassets. Use this volume name in command docker inspect name (Replace name in command with actual name) to get more information about this volume. You should see following info:
Mountpoint is the location of CMS assets such as translation files. Translation files is on this directory under i18n folder. For example this is the branding texts of CMS which you can update accordingly.
If you don't see this folder make sure you have updated your image according to Upgrade section of documentation.
The strings.xml can be found under /common/src/main/res/. This file has everything translatable.
You can generate latest XCode translation package by opening each project and from Edit Menu By Selecting Export for Localization. For more information on this you can use Official Apple Documentation