The one claim it makes
A certified translation into English is required for documents used in Ireland, and what comes back makes a single narrow claim. A named translator states that the English matches the source it was made from, and dates that statement. Everything else a reader might want to know about your paper sits outside the claim completely.
What it does not prove
It does not prove who you are, what you are owed, or that a record is up to date. It does not turn a lapsed paper into a live one. A certified translation in Southampton for Ireland reports what the sheet says and takes no view on whether the sheet is the right one for your purpose. That judgement stays with you.
When there is nothing to translate
Plenty of sets need no language work at all. A birth, marriage or death record from Southampton Register Office at 6a Bugle Street, Southampton SO14 2AJ is issued in English already, so paying to have it translated buys you nothing. Sort your pile by the language on the page, and order only for the sheets that are not in English.
The cost of the narrow claim
That narrow claim is priced at about £25 / page, which is why dropping sheets that need no English is real money saved. Standard delivery is 2–3 business days and the express option lands within 24 hours. Both run on working days. Neither figure covers the time a register office takes to issue a certified copy.