To the websites I think we have the best solution - because we know it forward what is gonna be implemented, and we can focus on it. For apps translations currently we don't have preferred/priority list in Zanata, only a project list that is based on alphabet order.
It would be easier for everybody, to know the "will be included surely", "optional", or "extras" or mark them somehow within Zanata. Also would be a great aid to have/access/generate only a summarized list based on the translator language with percentages.
Similar happens in the case of websites, where Robyduck tells to us witch has priority, and really matters in users experience. After this - I think we can concentrate on apps and parts that we provide within the distro, and those parts that our users are will surely meet after the first boot or everyday usage.