Complex sentence: Accurately measuring subjective pleasure (or pain) seemed awkward, and the thinkers of the time were aware of it; otherwise, they would not had renamed utility in imaginative ways such as subjective wealth, overall happiness, moral worth, psychic satisfaction, or ophélimité.
Split into simpler sentences: Accurately measuring subjective pleasure (or pain) seemed awkward, as the thinkers of the time were surely aware. They renamed utility in imaginative ways such as subjective wealth, overall happiness, moral worth, psychic satisfaction, or ophélimité.