I have about a dozen Kordes roses. Most from Palatines on multiflora root stock which I plant with the graft below ground. Seem to have decent winter hardiness with a little mulching, most of the above ground/mulch canes die back but they come back well for me and most seem to have decent BS resistance. Planted Lemon Fizz last year as an own root that I found at a regional big box store so waiting to see how that makes out. I have shovel pruned a few Kordes roses that didn't do good for me....Osiria--lacked vigor, several Freelander series (Kordes florist roses)--didn't like their blooms. Some of my fav Kordes roses are Antique Caramel, Pompon Veranda, Cream Veranda, South Africa, Lavaglut and possibly Lemon Fizz. I think you will have good luck with them in your z4 as well. Just remember to plant graft below ground & I even plant own root roses a few inches deeper than they were grown at the nursery. Here is a helpful graphic from the U. of MN:
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Planting graphic
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