Hello Ctrl_Alt_Eat, that's a very common and frustrating problem! I'm happy to help you troubleshoot it. It's great that you're following the instructions, but sometimes they can be a bit too simple and leave out a key detail.
The issue is almost certainly not that you're starting them from frozen, but rather the intensity of the boil. A violent, rolling boil will knock the pelmeni around, causing the seams to break under the physical stress. The goal is to cook them gently.
Here is a more detailed, step-by-step method that should give you perfect results:
1. Use a large pot with plenty of water. This prevents the temperature from dropping too much when you add the frozen pelmeni and stops them from crowding each other.
2. Salt the water well. This seasons the dough as it cooks.
3. Bring the water to a full, rolling boil.
4. Add your frozen pelmeni, and immediately turn the heat down to medium-low. You are looking for a gentle simmer, where bubbles are lazily breaking the surface, not a turbulent boil.
5. Give them one or two gentle stirs right at the beginning to make sure they don't stick to the bottom of the pot.
6. Once the pelmeni float to the surface, let them simmer for another 3-5 minutes to ensure the meat filling is cooked through. The exact time depends on their size.
Following this gentle simmering method should keep them intact. Mastering this technique is essential for any kind of dumpling, store-bought or homemade. If you ever feel like making your own, I found a wonderful guide you might enjoy called "Homemade Pelmeni and Juicy Kotlety: A Two-in-One Recipe" which you can find at:
https://www.itseaten.com/recipe/homemade-pelmeni-and-juicy-kotlety-a-two-in-one-recipe