No, if Alucard looks in a mirror, his reflection should be partially transparent. On the other hand, if he walks in front of a mirror as Genya Arikado, his reflection should be of him in his true form. If only his true hair color which is either blond or silver. Hell, if there is ever another sorrow game, there should be a scene with Arikado and Soma talking in front of a mirror at which point Soma notices that Arikado's reflection looks different. At which point, Arikado/Alucard transforms into his true form and explains everything in a nut-shell.
**FYI, when I say his true form, I'm talking about how he appears in SotN but in the cloths he is wearing at the moment. Seeing that Arikado is always wearing a suit and tie, his reflection would be of SotN but in a suit instead of what he wore in SotN.**