The financial requirement check is a reconciliation exercise, and the translation work has to support it.
The employer letter, in English (or translated if not), states the applicant's gross salary, employment start date, contract type and current position. UKVI uses it to anchor what the payslips should show.
Each payslip in the window then has to align with that anchor: gross pay roughly consistent month to month, taxes and deductions making sense, net pay arriving in the bank account named on the bank statement.
Each bank statement in the window has to show the net pay credited on or around the payday named in the contract. The credit description must be transliterated by the translator so the caseworker can match it to the salary line, not left as 'SAL CR' in the source-language script.
This is where a translation that 'looks fine' can still cause a refusal. If the payslip's net pay is 18,500 SAR for May and the bank statement shows a 17,200 SAR credit from the same employer on 25 May, those are inconsistent figures. The translation didn't cause the inconsistency, but a translation that doesn't surface the discrepancy in a translator's note (perhaps the difference is a one-off deduction explained on the payslip itself) leaves the caseworker to wonder, and wondering caseworkers send RFIs.