Hello.
When ONE user comment my story post (in Group) or FEW users comment my story post (in Group), system always display notification with the same language line.

I beleave it should be _PLURAL and SINGULAR variations when somebody comment.

Few or all of this:

APP_GROUP_STORY_USER_POSTED_COMMENT_ON_USERS_POST="%1$s commented on {b}%2$s's{/b} post"
APP_GROUP_STORY_USER_POSTED_COMMENT_ON_YOUR_POST="%1$s posted a comment on your post"

I suppose the same with Event's & Pages story's posts.

Thanks.