Create a global i18n model

Prerequisites

Go to the I18n Text & Translation tool and select Create.

Result: The Create or Enhance i18n Model dialog opens.
In Name, enter a meaningful name for the global model.

Keep hierarchical framework and UX design considerations in mind when you name the global i18n model, if you intend to create multiple global i18n models for different use cases.
If you want to enhance an existing global i18n model, turn on the Enhance Existing Model switch and select Base Model on which you want to enhance the existing model with deviating attribute entries.
In Fallback Locale, from the selection list, select a fallback locale that governs the language of text to display in the global i18n model if a certain locale defined translation is not filled on the user interface.
In Package, assign your global i18n model to a development package.
Select Create.

You have created a global i18n model.
If you turned on the Enhance Existing Model switch, you have created a derived model of the global i18n model to modify specific entries according to your use case.