Help us create a curated list of dictionaries for each shipping locale in Firefox

Hi localizers,

As hinted in a previous message, we are currently working on improving 
the experience in Firefox for multilingual users. That includes, among 
other things:
1) Adding a language switcher in Preferences to switch to another 
language that is already available on the system (i.e. already installed 
as a language pack).
2) Adding UI to preferences to manage basic interaction with dictionaries.
3) Add the ability, on release, to install a new language directly from 
Preferences (it would download, install and enable a language pack from 
AMO).

As part of #3, we also want to install dictionaries for that language. 
For example: user chooses to install Italian on an English build, the 
system will download the language pack and also install the Italian 
dictionary.

In order to do that, we need a curated list of dictionaries that will be 
installed with each locale, and we need your help and feedback to make 
sure that list is meaningful and provides a good experience.

Here's the first version of this list: 
https://mozilla-l10n.github.io/firefox-dictionaries/
You can also see the complete list of dictionaries available on AMO: 
https://mozilla-l10n.github.io/firefox-dictionaries/complete.html

This list was created by:
* Picking one dictionary when language has more than one available, 
usually looking at the number of users on AMO. The complete list provide 
a list of such locales.
* Verifying that the dictionary can be installed.

Ideally, there should be only one dictionary per language, but there can 
be exceptions. For example, the current list would also install de-CH 
and de-AT for German.

Here's the *help we need from you*:
* Install the dictionary currently suggested for your language, and 
check that it provides a good experience. If that's not the case, we 
should remove it.
* Determine if you need more than one dictionary, and why that's the case.

You can provide feedback by replying in this email thread, or in the 
tracking bug
https://bugzilla.mozilla.org/show_bug.cgi?id=1481375

Note that this list will keep receiving updates in the future, for 
example if a new dictionary become available, or if we start shipping a 
new locale.

Francesco