Is sincere repentance sufficient to erase the effects of imagining known women and sacred things during masturbation, and does that entail rights for them, or does repentance supersede what came before it?

Repentance for the sins you mentioned, which pertain to the rights of Allah the Almighty, is achieved by feeling remorse, immediately refraining from the sin, and sincerely resolving not to return to it. You do not owe any right to those whom you imagined. Watching pornographic clips is a whisper from Satan, and its prohibition is well-established.