I'm only a few paragraphs in but I'm already a bit confused by the way the author seems to use "falsifiable" and "falsified" interchangably when it is the forme

I'm only a few paragraphs in but I'm already a bit confused by the way the author seems to use "falsifiable" and "falsified" interchangably when it is the former not the latter that is critical to Popper's definition. What matters is that you make a claim that has the potential to be tested. i.e. there exists an observation that could potentially contradict your claim. And if this observation arises, the result is that the hypothesis has an opportunity to refine itself and the process continues. Newtonian mechanics were falsifiable, they were falsified in particular domains (the very small and the very large) and now they have been refined as they are still applicable given certain contraints.