1. Hmmm, seems you are the first actually: www.joomlaworks.net/forum/search?query=summary_large_image&childforums=1 - where exactly did other users ask that change (out of curiosity)?

2. The issue is most likely in your language pack, it's not a K2 issue.

OK I will do it! Thanks

I ask you: is it possible that your add some changes for everyone?

1/ In View>Item>tmpl > Change the image tag "summary" of the Twitter card to: "summary_large_image"? I have read that other users also requested it.

2/ In Administrator, mod k2 stats > the time is incorrect, it is "K2_DATE_FORMAT" (broked the hours and minutes) but it will be: "K2_DATE_FORMAT_LC2"

These are two changes that I always make manually every time I update k2 in my sites! ;)