From a reader:
Father, I spend a lot of time in Finland which has Europe’s smallest Catholic Church, [not to mention one of Europe's oddest languages...] both in terms of absolute numbers and in terms of percentage of the population. Nearly all the priests are non-Finns and often we don’t have a common language between us. I went to confession on one occasion and although the priest did his best and even read the prayer of absolution in English [Father should just use Latin. Sheesh!] I am certain he did not understand everything I said. [He doesn't need to understand you perfectly.] Although the seal of the confessional is absolute on the part of the priest could a penitent voluntarily ask a trusted friend or family member to act as an interpreter?
Yes, an interpreter is permitted. However, the interpreter who would consent to do this would then be bound to preserve secrecy about the penitent and content of the confession in a way similar to that of priests.
In the Latin Church’s 1983 Code of Canon Law we find:
can. 983 §1. The sacramental seal is inviolable; therefore it is absolutely forbidden for a confessor to betray in any way a penitent in words or in any manner and for any reason.
§2. The interpreter, if there is one, and all others who in any way have knowledge of sins from confession are also obliged to observe secrecy.
can 1388 §1. A confessor who directly violates the sacramental seal incurs a latae sententiae excommunication reserved to the Apostolic See; one who does so only indirectly is to be punished according to the gravity of the delict.
§2. An interpreter and the others mentioned in can. 983, §2 who violate the secret are to be punished with a just penalty, not excluding excommunication.
So, an interpreter who helps someone make a sacramental confession or… and PAY ATTENTION EVERYONE… anyone who gains knowledge of a confession (for example, overhears a confession) is obliged to preserve secrecy (can. 983§2). If an interpreter or “over-hearer” knowingly and willingly violates the secrecy of another person’s confession she commits is a mortal sin. Proper authority can impose on her “a just penalty, not excluding excommunication” (can. 1388§2).
Not only that, a person who falsely accuses a priest of breaking the Seal of confession commits a mortal sin and canonical penalties, including excommunication are imposed.