Quick first note and recap of some discussion outside GitHub:

It looks like the messages here are mostly exception messages. Since this is the first xamarin-android dependency to tackle exception messages, that raises some small questions about what kind of adjustments to make to the wording of the exception messages to help make them more easily localizable. Based on a first glance at the current wordings, I think maybe using full sentences where it's not too awkward might be worthwhile.

To give a tiny first example, maybe must not be null or empty can be adjusted just slightly to add the name of the argument at the beginning of the message. That will align it with some similar messages in dotnet/sdk and make it a full sentence:

 <data name="MustNotBeNullOrEmpty" xml:space="preserve">
-  <value>Must not be null or empty.</value>
-  <comment>Must not be null or empty.</comment>
+  <value>{0} must not be null or empty.</value>
+  <comment>{0} - The name of the parameter</comment>
 </data>

Though this is technically a little redundant since the exception also accepts the type name as a separate argument and surfaces it separately, the benefit is that the redundancy provides more context for the localization team.

Thanks for all the work on this! Here are a few comments and questions about the localization build setup. I'll plan to do one more pass to look through the .resx file and the message wordings tomorrow.

Nice work on the new message wordings! Here are ideas for a few little adjustments. One other little bit of tidy up that might be a nice finishing touch could be to alphabetize the entries by name in the .resx file.