I did say no definition is perfect. however, Robotech isn't much of a grey area. The original shows were in Japanese well before they were dubbed, and any sale to an overseas company was an after-thought. Same with Samurai Pizza Cats. By the "initial broadcast" rule those are anime adaptations. These examples are the prime reason I said
initial audience. They merely dubbed those, there was almost no original artwork added. "poorly translated" or "loosely translated" are both subsets of "translated". e.g. if a book was in French, and was loosely translated, nobody confuses that for an original work in English. The same, if you dub a Japanese cartoon "creatively" or just "badly", nobody confuses it for an original English cartoon (assuming they know that the original work exists, in both the case of a book or a tv show).
A proper grey area would be things that were commissioned for overseas production, but also broadcast in Japan at the same time, such as the Supernatural cartoon, or some Marvel/DC stuff, but those are pretty uncommon so they don't really cause much of a problem with actual arguments that can start. And anyway, those are from western franchises, and commissioned specifically to be shown in western nations from initial broadcast, so most people aren't going to confuse e.g. that Batman is an anime.
What Japan considers 'anime' is also irrelevant, because as you point out it just means 'cartoon'. It was stolen to have purpose for English speakers, which does tend towards the stylistic rather than geographic; eg most people do mean Dragonball or Inuyasha, not Astro Boy or That One Artsy Historical Drama With No Release In English.
Sure, what Japan thinks isn't relevant. However the term was coined in English to cover all Japanese cartoons, so that we
didn't need to ever specify "Japanese cartoon", because the word anime covered that. Saying that it
ever makes sense to exclude something like "Astro Boy" from what's considered anime just exemplifies the problem with trying to use that alternative definition as the primary one.
differentiating it as a specific style means that we'd have to start using redundant terms like "Japanese anime" vs "japanese cartoon" if "american anime" was a separate category to "american cartoon". Now, you have 4 categories, not two, to cover country of origin and subjective style. And the problem with that is exemplified by your off-hand comment that people
don't mean Astro Boy when they say "anime". What's Astro Boy then? A "Japanese cartoon", right, which we're now considering to be a
separate category to "
Japanese anime".
So the big problem is that now instead of having
two categories, we need
four to properly classify things, and we're starting to literally have a discussion about which
Japanese cartoons are the "real" ones that deserve the japanese loan word to describe them, and which ones get labeled with an American catch-all term, which is frankly preposterous.