What free software leaves out
Paste a birth entry into a translation site and Spanish appears at once. What does not appear is anyone's name against it. A certified translation for Honduras is not judged on how fluent the Spanish reads; it is judged on whether a person put their signature to the claim that the Spanish carries the same facts as the English.
Software also stumbles at the edges of a paper record. It guesses at a faded stamp, mangles a note written in the margin, and quietly drops a reference number it cannot parse. Someone producing a certified translation into Spanish in London works through those parts on purpose, because the signature at the end covers them as well as the clean printed lines.
Spanish is the fixed part of the job
A document put to official use in Honduras has to be in Spanish. That part does not move, whatever the paper is — a degree, a company letter, a birth record. An official Spanish translation in London is therefore the starting point of the file rather than a late addition to it, and everything else follows from that one fixed point.
The person who signs, and what the signature binds
The signature comes from a certified translator. The certificate of accuracy is a separate short page: it names them, gives the date, describes the sheet that was translated, and states that the Spanish version is a true rendering of it. One person's name sits on all of that, which is precisely what a website output lacks.
No oath sits behind the page. The work is not sworn before a judge and no court register holds the translator's name, so what stands behind the Spanish is an individual's signed word together with their standing as a certified translator.
What it costs and when it lands
The rate is about £25 a page, so the bill tracks the length of the paper rather than the language on it. Standard work is back in 2–3 business days and express work in 24 hours. The page rate does not move with the deadline you pick.
Your own certificate stays where it is
Nothing here needs your original in the post. Where the paper is a civil record, Westminster Register Office at 317 Harrow Road, London W9 3RJ issues fresh certified copies of birth, marriage and death entries, and a certified copy reads to a translator exactly as the first one did. That office works by post and by appointment, and it does not translate anything itself.