The language Liberia requires
A certified translation into English is required for documents used in Liberia, so any paper in the file that was not issued in English needs a signed English version beside it. A certified translation into English in Belfast creates that second document without touching the first, which stays exactly as its issuing authority produced it.
Records change after they are made
A civil record is not frozen at the moment of registration. Spellings get corrected, an entry is amended, a replacement is printed long afterwards on a different form. Each of those events produces a piece of paper differing from the last, and only one of them is the version a receiving office in Liberia will end up holding. Deciding which comes before any question of translation.
The signed statement names its source
A certificate of accuracy does more than declare a rendering faithful; it identifies what was rendered. The issue date, the reference number and the form of the document all appear on it, which is what makes the pairing checkable at a glance. It also means the source cannot be swapped afterwards — attach the English version to a different copy and the description stops matching the paper behind it.
Getting the current version in Belfast
Northern Ireland keeps its own civil registration, so births, marriages and deaths registered in Belfast are held by the General Register Office for Northern Ireland (GRONI) at Colby House, Stranmillis Court, Belfast BT9 5RR rather than by any registry in Great Britain. A fresh certified copy from that office shows the entry as it stands now, and ordering one means the older certificate in your possession never has to move.
What the choice costs
Charging is per side as issued at roughly £25, so the length of the version you pick is also the size of the bill: a full entry runs to more pages than a short form and is usually worth every one of them. Standard production takes 2–3 business days from a readable scan, and a 24-hour route is available at a higher per-page rate when a date will not move.