Fluent is a family of localization specifications, implementations and good practices developed by Mozilla.
It would be awesome if that type of translation was supported in Zanata. I understand it's going to take a really long time (if feasible at all) since it goes in another direction as most existing formats, but I personally believe it's the first "right" take at string translation for developpers and it would be great to see it working in zanata which is the first "right" take at translation tools for translators.
Quote from the wiki:
Software localization has been dominated by an outdated paradigm: the translation is just a dictionary of strings which map one-to-one to the English (en-US) copy. This paradigm is unfair and limiting to languages with grammars more complex than English. For any grammatical feature not supported by English, a special case must be added to the source code, leaking logic into all translations. Furthermore, creating good UIs which depend on multiple external arguments is hard and requires the developer to understand the grammar of the languages the product targets.
Design a DSL for creating expressive translations which can depend on many internal and external arguments.
Design a low-level API for parsing and formatting translations which keeps localizations isolated from each other.
Create a reference implementation which can be used to build localization frameworks.
Create a new localization framework.
Solve IO for all platforms.