Start with the paper you already hold
Chile reads official files in Spanish, so the English record you hold has to be paired with a Spanish one. Before any of that, though, settle which copy is going. Half the wasted time on this route is spent translating a sheet that was never the one being asked for.
For a record made in this city, Liverpool Register Office is where a clean copy comes from. It issues certified copies of births, marriages and deaths from St George's Hall, St George's Place, Liverpool L1 1JJ. A fresh copy costs little and keeps the one in your drawer out of harm's way.
Most people book a certified translation into Spanish in Liverpool once that copy is in hand. Work is done from a scan, so nothing has to be posted anywhere. The paper stays with you from the first day to the last.
What the translator signs
The Spanish version is laid out to follow the source page. Where a seal sits, the text says a seal sits there. Where a line is signed by hand, that is noted too. Nothing is tidied away, because a clerk is matching one page against the other.
Behind the text stands a qualified certified translator, who signs a certificate of accuracy. That signed line states that the Spanish says what the English says, and gives the reader a named person to hold to it. No court oath is part of this route.
An official Spanish translation in Liverpool is sent to you as a scan before anything is printed. Read the names and the dates at that point. A spelling put right in an email costs nothing; the same fix after the set is signed means the pages are run again.
Price, speed and the slip-ups that cost time
The rate is about £25 a page and it is counted on the source, not on words. Standard work takes 2–3 business days from the moment a readable scan lands, and the express lane closes in 24 hours when a date will not move.
The slip-ups are dull and easy to avoid. A dark scan that swallows a stamp. A page shot at an angle so the edge is cut. A middle sheet left out of a long record. Each one stops the job before it starts and adds a day to the wait. Send every page at once, in colour, and all three go away.