Garden Mysteries..

Can anyone help me and identify this plant please? It was given to me as a tiny seedling by a friend who planted the seeds out of a packet which should have been purple de Milpa tomatillos... which it obviously isn't. Clearly it is related to celery. The leaves taste of celery but in a very aromatic, possibly citrus way. The stalks are completely round and not celery shaped. I am thinking perhaps it might be Parcel, or Hamburgh parsley, or some kind of leaf celery. Any thoughts?
Another mystery to solve. Last year I saved some seed from a Sungold cherry tomato. These are an F1 hybrid so I was expecting something slightly different, but... they will not ripen! They have sat in this green/gold state for about 5 weeks now. All other tomatoes around them in the greenhouse are ripening fine. I have even picked about a dozen and sat them in the kitchen among all the other ripening tomatoes for about 4 weeks .... they do not ripen!! They still taste green, why are they not ripening.. anyone?