The language Russia requires
A certified translation into Russian is required for documents used in Russia, so an English record from Northern Ireland needs a Russian version beside it. Only the new text is certified. The English sheet stays exactly as issued, with nothing written on it and nothing taken away, whichever shape of the work you end up choosing.
A base form and a step on top
Two shapes exist here. The plain one is the Russian text with a signed, dated statement of accuracy bound to it, written by a certified Russian translator. The other keeps that and adds a further signing step above it, and notarisation is available for the files that call for one. A certified translation in Belfast for Russia is the same piece of writing either way.
Why the choice belongs at the start
Making the call early keeps the job to one run. Order the plain shape, find out later that the longer one was wanted, and the work is reopened rather than continued, because the statement has to be signed afresh over the enlarged set. Nothing already written is lost, but the calendar is, and on a 2–4 business day run that costs more days than it sounds like.
Where the Belfast record comes from
Northern Ireland administers its own civil registration, so a birth, marriage or death registered in Belfast is issued by the General Register Office for Northern Ireland (GRONI) at Colby House, Stranmillis Court, Belfast BT9 5RR and not by a registry in Great Britain. That office works by post. A certified copy ordered from it can go to the translator, which keeps the sheet you own out of the job whichever shape you pick.
Cost and pace
The rate is about £25 for each page as issued, and a certified translation for Russia is counted in sides of paper. Standard production runs 2–4 business days once readable scans exist, with a 24–48 hour route where a date is close. Both figures describe the writing itself, and anything arranged on top of it carries its own timing rather than borrowing these.