FYI, you should have had Apple or an Apple Authorized Service Provider examine the laptop as it may have qualified for a free Apple keyboard repair program (it won't now):
https://support.apple.com/keyboard-service-program-for-mac-notebooks
Did the center silicone cup tear off or just the silicone dust cover? I would not even worry about attempting to fix the silicone dust cover.
If the silicone cup tore off, then the key won't work without it. While you may be able to superglue the silicone cup back into place, it definitely depends on how it tore off. I doubt it will last for long at all and you need to be very careful not to get glue in the wrong places. When this has happened, I will take an old identical keyboard and cut off the silicone cup and a bit of plastic around the base of the silicone cup in order to get a nice surface for the superglue. The problem with gluing the broken silicone cup you have is that glue does not really stick to silicone and you are trying to glue a flexible item. The base of the silicone cup will flex when the key is press so it will fail in short order.
You also need to be very careful reattaching the key cap since it is very easy to break the lugs on the key cap and the scissor/butterfly mechanism.
FYI, here is the current list of the publicly acknowledged free repair programs for various Apple products:
https://support.apple.com/service-programs