Arguta will be fine it is very hardy. The stems may have froseted back but new ones will sprout up, mine aready are from the freeze as well.
As for digita X meruensis (correct spelling)it may be ok we are warming up. I would say if the plant didnt turn to mush they should be ok. I would not be surprised if you dont get a few seedlings popping up. If you do get some they should be different then the parent. They are like snowflakes no two look alike.

Thank you for your advice, Mr. Impatiens. I am relieved that my impatiens is okay. Thank you for explaining how seedlings look like. This is a tremendous help. Without your advice, I would have weeded it out. Also thank you for the spelling correction as well. These impatienses are our favorites and got them from SF Botanical Garden. Since it grows so well here (Sunset area in SF) and has so many other beautiful kinds that I learned from your web site and Annie's Annuals, we were going to get more. And we are glad to know we could for it can survive the frost! But we will plant it in warmer area of our backyard. Thank you again!