Even with my most loved adaptations there is room to critique and and "wish they had done X differently". Being heavily engrossed in the DC Comic fandom where both live action and animated adaptations occur around various story archs several times a year I see this process constantly, and as a result it has made me more lenient concerning adaptations than a lot of people
Even with some adaptations I have to question what they were thinking cutting X out or changing X plot-specific thing.
Most of the time I can just brush off various adaptations as "It's just an AU to the original" and it helps me sleep at night.
I used to get so upset with differences between versions as a teenager it would really tax me and my sleep would suffer, so I had no choice but to make peace with it instead of gnawing on it like a surly dog with a bone. So for me at least the "Alternative Universe" excuse really helped me.
However I realize not everyone is in agreement with this kind of logic and it bothers them a lot.
As for Astro Boy in specific I am satisfied with the translations and dubs of all three series, is there room for improvement? YES, particularly with the editing. However overall I am satisfied, which if this were a paper being graded that would be about a C.