Hi,
a button inside a MSO state can see the MSO where it sits in.
You cannot see MSOs outside of the MSO the button sits in. For example other MSOs on the page.
Maybe you can work with MSOs that are nested inside of MSOs?
Two ways of nesting MSOs to states of an MSO:
1. Anchor a MSO to a text frame inside of a state of another MSO.
2. Add a new, generic MSO to a graphic frame inside of a state of the MSO.
You can do that by scripting only.
With option 1 the button cannot see the anchored MSO.
With option 2 the button can see the added MSO.
How to add a new MSO to a graphic frame:
Re: Animation not work in NESTED MSO
Downside of option 2: You have to add all of your states to the new MSO.
You cannot use a prepared MSO and simply add it inside a graphic frame. Paste Inside is grayed out.
Here an example from my German InDesign:

The green object is a MSO I added by scripting to the frame with the blue frame edges and no fill.
The BUTTON can see the MSO where it is positioned in, named "MSO on Page". Nothing unusual here.
But BUTTON can also see the nested MSO named "nestedMSO" inside the graphic frame named "Frame with MSO inside" of State-1 of MSO named "MSO on Page".
The magenta frame is just another frame in State-1 of "MSO on Page".
"Ebene 1" is just "Layer 1" of the document. "Schaltfläche" means "Button".
Regards,
Uwe