One type of ceremony that is very popular is a civil and celebration ceremony. The format means you will have a celebrant, who is also going to be your translator and who will be leading through the ceremony from beginning to end.
There will be also a registrar, who does the civil part at the beginning of the ceremony, right after the welcome greeting and introduction of the celebrant. During the civil ceremony the celebrant will translate from Portuguese into English (or other language) and after the registrar has finished the registrar leaves and the celebrant continues with a celebration ceremony in English. Readings, Ring exchange, signing of certificate etc are all part of the celebration ceremony.
In some cases the registrar may stay till the end of the ceremony. This is something we can not predict, because we usually do not know which registrar will be delegated to do your wedding.