"...- do Sound engineers listen to the finished master on a TOTL hi-fi system having a more "normal configuration" i.e. like many of us have in our houses, to ensure their end product will sound just as they want it?..."
Short answer: Some do but very few. Some studios will have a pair of home audio speakers in the mixing room.
Short answer: Some do but very few. Some studios will have a pair of home audio speakers in the mixing room.