The TranslatorHQ system is constantly checking for changes. It does this based upon the Stock or sell price being different OR the last changed date in Retail Express being triggered.
If you change the data map then any changes that happened before that date will not be “seen”. Only if the product is marked as recently changed in REX will it make any change. The same applies if you make a change in your eCommerce system it will also not be "seen" by the integration.