I have not closely studied the specific translation of the texts bto which you refer and so can't comment on their authenticity or lack thereof. The Hermetic corpus largely took its shape in the first century CE although, of course, many of the texts dated far back into the Egyptian past. Re. the
harsh attitude towards magic by early Christianity--and later too!--it was part and parcel of the attempt to quash anything whatever that seemed to reflect or echo Pagan beliefs and practices. The truth was that the connections were so close and so deep that Christianism--as I describe what the Church became during the third and fourth centuries CE--wanted to obliterate Paganism entirely from the scene.