The monitor currently takes care of these problems for you:

Manual change of data on destination product - updates the database

Source data change without a need to change the destination data - updates the database

Source data change that has suddenly data integrity problem that is required - updates the database, change destination quantity to 0

Source data changed such as quantity or price - validate if an update is required - if so - updates the database, changes destination quantity, changes destination price

Source doesn't exist anymore - 404 not found - change the quantity to 0 (need to be careful with this part because it might also say we have probably with the source marketplace integration - such as API keys incorrect)

Source suddenly received more quantity - change the quantity to 1 or to previous quantity - need to check

For detailed information on how prices are calculated: