If it were that simple, translators would already have been made redundant by computer programs. Even if a few words are replaced by American terms, there will still be significant phraseology issues.
Not at all. I've NEVER believed in automated language translations, as they often spit out gibberish. I've long favor Fivrr for translations, because for a few bucks, you can get a quick translation from someone who actually knows and is fluent in the language.
The same is true with reader feedback. Granted, you need to vet the suggestions, but if you get something wrong, you'll usually have several people with enough knowledge to alert you before you get too far afield.
I've deliberately ignored a couple of such suggestions because, although they represented the normal American jargon, they would make the story far less comprehensible to non-American readers.
That's always true. While you've got opinions based on experience, you've also got to merge them into an existing story. Typically, when I get feedback, I'll respond by telling the reader how I used the information, and if it doesn't fit into the story, I'll explain that, or if I need to rewrite their suggestion, I'll show them how I changed in (in case I make the situation worse with a last-minute typo).
Generally, I've had a very good record with reader suggestions, though I do vet them. Often, when I get a new editor, I'll compare how they handle writing issues vs. how my other editors do, to determine whether they have any clue as to what they're talking about. If not, I don't argue with them, I just quietly shuffle them aside and stick to my more reliable editors.
The key, though, is to have faith in your own story. One regional dialect can't be superimposed into another region, and one user's 'experiences' are often tainted by outside exposures too.