^ I adhere to the idea that the spheres are the same in 12th - 26th century, the only difference is that by the 26th century there is more of them and therefore Procyon V would be now part of the Delphic Expanse.
So if the spheres are destroyed in the 22nd century, they do not have to be destroyed in the 26th.
But this doesn't change the fact that we have not heard the last of the Sphere Builders. They are still safe in their own realm. They do posses time travel technology (a part of the Xindi prototype came from the future, there was the short visit to the 21st century, and they shared the technology with the Borg in the !24th century).
If they breeched the universe once, can they not do it again? Who is to say that they did not move shop and are operating somewhere else?
However there are limitation to this technology - why didn't they attack sooner?
Could they predict the future only for something over 400 years? The only advanced race they could use in the Delphic Expanse were the Xindi, an earlier attempt the Triannon destroyed themselves?