Perception trends at least tell us something, especially when a country is compared with itself over time. Ukraine’s has improved remarkably. Yes there are limits to perception polls, but that is one of the few universal metrics.
As for Zelensky, a few things. First, he was in the Pandora Papers, not the Panama Papers. Second, just because someone is in either the Pandora or Panama Papers does not mean that they were engaged in wrongdoing. So for now, I’m withholding judgement on him being a “massive fascist crook”.