Counter suggestion: the ASCII-smiley to emoji translations in Discourse’s emoji plugin should be configurable in the admin interface.
So far, I’ve been dragging around a patch file that gets applied on Discourse updates, because I’m my users are accustomed to stuff like ^^ for , ^^; for and T_T for , and really don’t like some of the default translations, e.g. :D which should be instead of the normal smiley…
With this in place, the Vanilla2 importer could just install a translation table that matches the emoticons the Vanilla2 emoji plugin defines instead of converting the posts.