A name is copied, not converted
The first rule of this work is that a person keeps their name. Translating it would break the link between your Spanish set and every other record that person owns — a passport, a school file, an old entry in a register. So the letters stay put, accents and all, exactly as your page prints them. Where two of your papers disagree, the translator says so on the page instead of hiding the gap.
The language Ecuador reads
A certified translation into Spanish in London is required for papers that will be used in Ecuador, whatever language they were issued in. An English page alone leaves a clerk nothing to act on. The Spanish becomes the text that is read, and your English sheet travels beside it, so any name, date or number can be checked across the pair without a word of English being understood.
Dates spelled out, numbers left alone
Two habits do most of the work here. Dates get their month written in words, which kills the day-month muddle that figures alone create. Numbers are copied straight, because a registry code is a label rather than a quantity, and changing so much as a leading zero would make the two sheets stop matching. Small rules, but they are what stops a set being handed back.
The sheet that names who decided
Every one of those choices belongs to a named person. The certificate of accuracy carries that name, the date, and a plain statement that the Spanish is true to the source. A certified translation in London for Ecuador is judged on that sheet as much as on the prose above it. Keep it with the pages and the copy they were made from; separated, it points at nothing.
Your own paper never moves
None of this asks for the sheet in your drawer. Scans carry the job from start to finish, so the record you may need again stays with you. Where it is a birth, marriage or death entry, Westminster Register Office at 317 Harrow Road, London W9 3RJ issues a fresh certified copy that can be used in place of the one you hold, which is the safer habit whenever a set is going abroad.