1) The change in deflector colour is derived from the shields, not the actual deflector.

2) The Sovereign's defllector can never be changed, because when they did an art-pass on it a year or two ago, they changed it to be more inline with the IP - there is no 'glowing blue dish' on the Sovereign class, and the Sovereign's deflector (unless you use the Noble variant) in STO remains true to this, and is not affected by texture modifications that affect other ships. (You do, however, get the 'particle' effects from deflectors such as the MACO, Aegis, Borg and Omega)