Imagine you are a fat person. In the past you would try to drop some weight by eating salads and drinking diet soda. What you would be doing is INCREASING your PUFA intake with salad dressing but DECREASING your fructose intake with diet soda. This could be expected to show some mild improvements in your health metrics if you are part of a clinical study. But these clinical studies don't test for the combination of PUFAs and fructose. They are usually just isolating their PUFA intake. The measurements are almost never given in the context of fructose intake.
When you see a dietary study that shows an improvement with increased PUFA consumption, make sure they are taking measures of participants who are not decreasing their fructose intake. How much better would the study participants do with a low PUFA diet? Hopefully, some day, we will know.