I don't agree with you on this. Technology tends to be interdependent on other technologies. Thus i think it would be totally plausible to be able to determine something about the species other then they were better then us at flight. At the most basic level assuming they had flown to earth we would know they had a mastery of space flight and potentially aerodynamics (assuming they landed). This would mean they would have to have mastered certain areas of Physics and thus have an understanding of the areas of mathematics necessary to understand this. In addition most modern engineering problems require large mathematical solutions which would also suggest for advanced space flight they would also need some sort of high speed information processing / simulation capabilities i.e. they developed and discovered some form of computing. I've only written a short synopsis but there would be a ton of other areas they would likely need to have advanced in as well such as material sciences (to handle vacuum, re-entry, strong acceleration), biological sciences (assuming craft had passengers, if it was artificial or a "drone" then this links back to my point on computer development)
Unless they did not do it how we would do it. My whole point is the tech is interdependent don't have the wheel don't get the pulley etc. The new world did not apply the wheel but somehow figured out road building irrigation running water etc. So if I see a paved road should I assume wheels? In a similar way aliens visiting only tells us they can visit. It implies a lot of stuff but it only tells us one thing. There seems to be lot of projection in what you have written. I partially cede that some tech may be inferred but only in a general sense we know nothing about their physical requirements or limits. We don't even know that mathematics is the only way to arrive at tech. (actually if you look at the history of the jet engine it does not seem to be true) As for moral and ethical "advances" I assume you agree that can not be inferred at all.