Unfortunately there's no such interconnection, there must be a master object which can be edited and your goggles follow those edits. There are two ways to get that master-slave relation
1) place an object with link. The original linked version can be edited and the placed copies follow
2) drag your object to the symbols panel. You can drag from there as many copies to your artboard as you need. The instances can be scaled, flipped and rotated, but not colored or deformed in details. Double-click the original or one of the instances in the symbols panel to open the original in Isolation Mode for edits. Click the exit icon when you are ready
You can make a symbol instance independent. Right-click it and select "Break link".
Both methods have a drawback. If you want to tune the master version, you must do tricks to have the rest of the image available for reference.
If you double-click an instance of a symbol for edits, you have the original non-scaled and non-rotated version under edits.
I wouldn't tease myself with this complexity, if there's only 2 identical pieces needed. Having the parts as group it's easily duplicated on the fly. You can reach any part inside the group via the layers panel. Lock or hide other parts which are too near or above to keep them safe.
You can make perfectly placed copy by having a reference object for the place where the copy should be moved to or with Object > Transform > Move > Copy.
Lenses seen from aside are not round. They are ellipses and the protective edge covers a lens partially.
Avoid green glow. It's the output color to user's eyes. Any green glow is dangerous leakage which makes the user perfect target for a sniper. If you want some color for stylistical reasons, let it be orange. It must not look out internal glow, but a partial reflection of the used lens material.
Watch some photos of the lenses of the binoculars. All glosses and reflections can be quite same. They are originated from external light. Or see the following drawing. It has ellipses, a couple of lines and fills: