This must be a 1st order network. At 500Hz, the tweeter and the capacitor have the same impedance, so phase is 45 degrees. Honestly, I wouldn't consider this to be bad at all.Consider all the capacitors inside an amplifier. The laws of physics are the same in our amps - each RC network has a corresponding phase shift. Most of the caps are fully in the passband because coupling caps and bypass caps are set for 10Hz or some other very low frequency, so their phase shift is negligible in the audio band. But tone controls and equalizers are killers for phase.