The Italian is incorrect, since article 29 doesn't contain the word "addetto".
Il responsabile del trattamento, o chiunque agisca sotto la sua autorità o sotto quella del titolare del trattamento, che abbia accesso a dati personali non può trattare tali dati se non è istruito in tal senso
http://www.privacy-regulation.eu/it/29.htmHere is the English:
The processor and any person acting under the authority of the controller or of the processor, who has access to personal data, shall not process those data except on instructions from the controller...
http://www.privacy-regulation.eu/en/29.htmYou'll have to find a way around this by rewriting it to correct the mistake.