So, if I can repeat what I think you are asking:
You have a lot of objects that you can use HISM to represent. These objects can have transformations you want to be able to manipulate in the main editor window, individually. On top of that, you’re mixing in the asteroid example.
Let’s see if I can clarify it all in one fell swoop. It all comes down to a single mesh. The HISM is a set of transforms for that mesh. You can have 1,000 of them, 1 of them, or 1 million and it’s still one mesh that’s draw that many times. The beauty of the HISM is that it’s the same single mesh’s data that is draw multiple times. That’s one HISM object with however many copies of it you want to draw. To further clarify, if I have that mesh used in 5 blueprints, it’s still one mesh.
With that said, to answer the first - I believe the answer is no, you can’t edit out-of-box the individual instances without a bit of magic. If you need massive tweaking of them, I would recomend building a system that takes placeholder objects and converts them into transformations for your HISM. I believe RAMA has a plug in that does this for you as well, and 4.22 is coming with it, or something similar to it.