Thats a bad example imo. Its more like "you need to acquire 1XXX gold by using this few things that give you unknowable amount of gold. some things may give you wood instead of gold but you'll never know. also if you do things in a certain order you may earn more gold but you'll never know that aswell. trial and error, trial and error... Oh, you gathered 1100 gold? well, I wanted 1200 gold, mission failed."
Your example is better, but since you knew what i wanted to say, it wasn't completely false either.
And if you get wood instead of gold, you can imagine. There is a logic behind what training you chose increases which stat. And even when you're wrong, with most girls you can make a few mistakes, since you will know by then what your action did and if it was a good choice or not.
And for the amount: If the wife is to be submissive for example, just try to increase her subissivenes as far as you are able to. That's what you would do in real life too. Since it's a game and a game is always numbers, everything has to be measurable. But to succesfully complete training, you don't have to know the numbers, just try to increase what is needed as much as possible.
What it makes more complex though is, that each Wifetrainer has different strengths and therefore you can use that for a different outcome or another way to solve it. For example, Playboy is better in increasing desire, therfore it's better to seduce instead of to dominate.
EDIT: But you're right, that sometimes that outcome is not at all as you expected it to be. But that's a problem with all games that simulate "reality". For example, i played another game, where i had the decision to kill an assassin or take him prisoner. I thought, great,, i take him as a prisoner and then i can get some infos why he tried to assassinate me. But instead i was seen as softy and there wasn't any interrogation. Makes no sense to me, but to the guy who designed the game it seemed to have made sense.