Can Invisalign Help Bring Down a Canine Tooth?

Moving the tooth back down with an elastic is a great idea. You probably don't need Invisalign for this simple movement. Instead I would consider placing one button on the upper canine, and two buttons on the opposing canine and first premolar. Your elastic would form a small triangle as it stretches between the buttons. I would recommend wearing a clear overlay retainer over the lower teeth to prevent the lower teeth from moving also. An upper bonded retainer afterwards is indeed highly recommended. This kind of vertical relapse is not uncommon after guided eruption of an impacted canine. Good luck!

You can use invisalign to erupt a canine tooth, but it will need a clear button at the gumline and an elastic that will go over the tray to erupt the tooth, it won't come down with just the aligner, but it can be done.  You may need some form of a bonded retainer afterward to keep the tooth in place.

While Invisalign is very good in many situations, it is NOT good at erupting teeth. Unfortunately, you would have to go back into conventional braces. Talk to the orthodontist about some other form of retention, once it is brought back down into correct position.