Combine frozen cherries, sugar, and cold water in a pan over medium-high heat. Mix cornstarch with extra cold water, stir that in once the cherries are warming, and cook until thick. Chill it in the fridge so it spreads easily.
Bloom the yeast with warm water until foamy. Mix in milk, sugar, and eggs, then add bread flour and salt, forming a shaggy dough. Blend in room-temperature butter and knead about 10 minutes until smooth.
Roll the risen dough into a rectangle. Spread chilled cherry filling, leaving a margin. Roll tightly into a log, cut into 12 pieces, and place in the pan. Let rise again for 30 minutes, then bake at 350°F (≈ 177 °C) for 30-35 minutes until golden.
Beat butter, cream cheese, powdered sugar, vanilla, and milk into smooth frosting. Cool baked rolls about 15 minutes before spreading the frosting so it holds a nice texture.