The polarized infrared reflectance and Raman spectra of the three quasi-two-dimensional β''-(BEDT-TTF)4 [(H3 O)Fe(C2 O4 )3 ]⋅Y bifunctional charge-transfer salts, where BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene and Y=C6 H5 Br, (C6 H5 CN)0.17 (C6 H5 Br)0.83 , (C6 H5 CN)0.4 (C6 H5 F)0.6 , have been measured as a function of the temperature. Signatures of charge inhomogenity have been found in both Raman and infrared spectra of the β''-(BEDT-TTF)4 [(H3 O)Fe(C2 O4 )3 ]⋅Y superconductors. A 100 K transition to a mixed insulating/metallic state is clearly seen for the first time in the temperature dependence of the electronic spectra of superconducting β''-(BEDT-TTF)4 [(H3 O)Fe(C2 O4 )3 ]⋅C6 H5 Br. We suggest that this phase transition is due to subtle changes in the ethylene groups ordering, which are related to a structural phase transition in the anionic layer. The infrared and Raman spectra of quasi-two-dimensional metal α-'pseudo-κ'-(BEDT-TTF)4 [(H3 O)Fe(C2 O4 )3 ]C6 H4 Br2 are also investigated.