Well... actually if the grille is totally inside your unit compoud, and did not affect any beam/pillar structure, its beyond management's control/rules.
As per ur photo, if we don't treat it as grille, its just an internal silver decoration kan?

So either talk strata rules with them or tell them that is not window grille,that is your inside house feng shui decor saja... else, listen to them and change saja...