Polarized Raman scattering spectra of distorted R over(3 m, -) elpasolites Cs₂NaAlF₆ with a Cr³⁺ content of 0.1, 0.5 and 3.0 at% have been studied at both room temperature and 16 K. A shoulder located near the very intense band assigned to the AlF₆^3- A_1g mode indicates that the guest ion causes only small perturbations to the host lattice. Magnetic susceptibility measurements performed on the 0.1, 0.5, 3, 10 and 50 at% samples show that for particular concentrations the Cr³⁺ ions are not isolated, but participate to inter and/or intra-cluster magnetic exchange.