How different experiences can be!
I have US119 for about ten years now, first potted than inground in a glashouse. No flowers yet. It is really slow to flower even when I admid that it did not always receive the best care. (For breeding, I also bought Sucrena, one elder of US119. I have now many flowers but all are pollen sterile. Also frustrating, especially because C. ichangensis flowers at the same time.)
Regarding the minimum temperatures I can only emphasize what Ilya wrote that the special growing conditions play a bigger role. I had a number of Swingle 5 Star seedling, most looking exactly the same as if they where nucellar. All died in my garden in their first winter. But we had only -12°C (10,4°F) in mid winter when they were still expected to be dormant. Yet, the original Swingle 5 Star from Ilya took -16°C (3,2°F) without much harm. Then Yuzu performed better than Poncirus in 2021. Poncirus lost a lot of twigs in late spring frost Yuzu lost only its leaves. Regarding US119 I would say. Take hardiness claims of others as your starting point but test them yourself. Good to read from you snack that you made better experiences than others with US119.