The Strata Manager is advising that as the glass tinting was added (by you) some time after the date that the Owners Corporation’s (O/C) glass door and panels were originally installed, and as the O/C is only required to replace items such as those to their original state, that’s minus the glass tinting.
That’s a hard-line approach but under the provisions of the (NSW) Strata Schemes Management Act it’s correct, unless of course you originally sought and obtained the consent of your O/C to “alter or change” their Common Property by fitting the glass tinting to their glass door and panels.
I’m guessing that you didn’t obtain the O/C’s consent, but if it’s any consolation at all you’re no worse off as any consent would typically include conditions requiring you and subsequent owners of your Lot to be be responsible for all on-going maintenance, repairs, and replacements of the tinting, and as a worst case for the glass door and panels themselves.
So you’re probably in front, but before you consider new tinting, I’d suggest that you seek your O/C’s consent to the installation of that in advance, and try to negotiate some better conditions such as some shared cost should the O/C again need to maintain or repair its Common Property.