find and replace a character in text comparing leading and trailing text.
(?<=\d+),(?=\d+)

Demo:
https://regex101.com/r/eINbxm/1


find and replace comments in the end of abap code after period.
(?!.\S)(".+)

Sample data:
    append 'ActualDeliveryRoute' to LT_FIELDNAMES. " 'ACTUALDELIVERYROUTE' ).
    append  'ActualDeliveryRoute' to LT_FIELDNAMES.
    append 'ActualGoodsMovementDate' to LT_FIELDNAMES. " 'ACTUALGOODSMOVEMENTDATE' ).
    append 'ActualGoodsMovementTime' to LT_FIELDNAMES. " 'ACTUALGOODSMOVEMENTTIME' ).
    append 'BillingDocumentDate' to LT_FIELDNAMES. " 'BILLINGDOCUMENTDATE' ).
    append 'BillOfLading' to LT_FIELDNAMES. " 'BILLOFLADING' ).
    append 'CompleteDeliveryIsDefined' to LT_FIELDNAMES. " 'COMPLETEDELIVERYISDEFINED' ).
    append 'ConfirmationTime' to LT_FIELDNAMES. " 'CONFIRMATIONTIME' ).