Q: Is there a rubric that when transferring a ciboria from the tabernacle to the altar it must be held high?
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A: No, there is no such rubric.
When the deacon or reader carries the book of the gospels in procession, it is to be carried “slightly raised.” It would always be appropriate to carry a ciborium with respect.
Still, if this is taking place during Mass, the rubrics of the Mass de-emphasize the use of the tabernacle in favor of having reverences directed toward the altar. I treat this in my book, Eucharistic Reservation.