Are all the artifacts in the game actually present?

Roman2211, if you want a proper, detailed answer to your question, please ask it more clearly. It is known that in "Heroes 3" there were artifacts (composite ones) that are described in the game's resources, but were never used in the game. See FizMig, section 3.9 for more details. These artifacts were used in some mods, for example, in WoG.