@Michelle Xue see the discussion here https://usergroup.netsuite.com/users/forum/platform-areas/customization/suitescript-2-0-custom-code/427569-record-getvalue-errors-if-field-name-is-built-programatically there are cases where string concatenation is not detected by the netsuite api to be a string

This is the related defect filed.

Defect 490659 : SuiteScript 2.0 > setCurrentMatrixSublistValue > sublistId > String type > SSS_MISSING_REQD_ARGUMENT

Alternate Solution: var sublistId = "price" + CURRENCY_ID; To var sublistId = String("price" + CURRENCY_ID);

The Urgency level assigned to your defect is U7.