Country variant grammar

For most of the supported languages there is a country variant String array. Do you plan to support country variant grammar rules like you would have in spelling? Also do the rules currently specify the country variant for which it applies or do they apply countries to all by default?

e.g.

May be identified as errors by a British-English grammar checker, but not a US-English grammar checker:
(1) The names given to the characters were “Annabelle,” “Zach,” and “Cody.”
(2) She practiced playing the saxophone
(3) I lost my key
Rationale
(1) The sentence uses US-English punctuation (where punctuation appears inside of quotation marks)
(2) The sentence uses the noun ‘practice’ instead of the verb ‘practise’ (a distinction not recognised in US English)
(3) In British English, the sentence should include have – i.e. I’ve lost my key

May be identified as errors by a US-English Grammar Checker, but not a British-English grammar checker:
(1) The names given to the characters were “Annabelle”, “Zach”, and “Cody”.
(2) He’s got much better at tennis
(3) He had a sawn-off shotgun
Rationale
(1) The sentence uses British-English punctuation (where punctuation appears outside of quotation marks)
(2) In US English, the past participle of ‘get’ is ‘gotten’ – i.e. He’s gotten much better at tennis
(3) In US English, the past participle of ‘saw’ is ‘sawed’