You can't really confirm these "Human-Chimp" skeletons, since you can never get any DNA evidence from them proving that they're the real missing link.
Chalk this one up in the "Junk Science" category.
No one has claimed that Pierolapithecus is the missing link, only that it has characteristics and the right age that one would expect to find in a missing link. Words like "proof" and "proving" don't have a place in this conversation. No one can prove anything here, they can only assemble evidence. Then we look at the preponderance of evidence and assess reasonable doubts. There is never a final verdict, only strongly indicated conclusions, on an investigation that remains a work in progress. That's not junk science.