Currently if I try -

{{#str}}{{country}}, countries{{/str}}

It fails because we are literally passing

{{country}}

to get_string() which then gets cleaned and ends up with get_string() throwing an exception about an empty identifier. In my use case I get a user record from the DB and want to translate the country, so 'AU' becomes 'Australia'. We currently do this in lib/myprofilelib.php by doing get_string($user->country, 'countries'). This will not work in templates.