Who is allowed to sign the Serbian text
Bosnia and Herzegovina reads official papers in Serbian, and it does not take just any Serbian text. The person who writes it has to be a court-appointed translator, a sudski tumač, listed by a court and holding a numbered stamp of their own.
So a sworn translator is required here, and that is the main way this route differs from a plain certified job. The oath is taken once, before the court that lists the translator. Every file they sign after that carries the weight of it.
You order a certified translation into Serbian in Liverpool and the file is routed to a listed translator. Nothing about your English paper changes. It stays as it is, and the Serbian sheet is added to it as a second, signed document.
The stamp, the seal and the bound set
The finished set is more than loose sheets. The Serbian text, a copy of the English source and the translator's statement are bound together, then stamped across the join. That stamp is what stops a page being swapped out later.
The stamp carries the translator's name and register number, so a clerk on the receiving side can trace who did the work. Keep the set whole. Pulling a page out to photocopy it breaks the seal, and the bundle then has to be made again.
An official Serbian translation in Liverpool is delivered as a scan first, so there is a chance to read it before the paper set goes out. Errors in a name or a date are cheap to fix at that point and costly once the bundle is stamped.
Cost, speed and the paper you start with
The rate for this route is about £25 a page, counted on the source page rather than the word count. The court stamp and the bound set are part of that price. A short civil record is one page; a long court judgment runs to several.
Standard work takes 2–4 business days. A listed translator is a smaller pool than the open market, so the queue moves a little slower than an ordinary job. When a date is fixed, the express lane brings it down to 24–48 hours.
The paper you start from matters as much as the text. Liverpool Register Office issues certified copies of births, marriages and deaths from St George's Hall, St George's Place, Liverpool L1 1JJ, so a fresh copy can be ordered instead of risking the one you hold.