Right. We have access to digitized papyri and other resources, but they're not all going to be translated (unfortunately).
BUT we can still verify scholars' readings and, with the help of people like Bryan and Eikadistes , get translations literally right from the source. This is another incentive for *everyone* having at least a rudimentary understanding of the ancient Greek, at least the alphabet (and paleography... And grammar... And... And... And ).
That second question is a good one, and would have to be answered on a case by case basis. Hopefully, books and papers and websites cite what translation they're using or if it's original.
LOL. None of this is easy. And taking translations at face value and without question is fraught with pitfalls!