No independent peer review has this tested. The circumstantial evidence for this is good but leads to expectations that indicates a limited applicability and a temporary, small effect. This is not a Nuremberg funnel.
The font was developed by people at a university at RMIT’s Behavioural Business Lab.
And the psychological base theory for this is called ...
The standard clinical research assessment method for evaluating reading performance seems to be the New International Reading Speed Texts (IReST.) cite 1 cite 2 cite 3
As far as I've been able to discover, there's never been any studies done on "PX Project" using the IReST. Perhaps a better researcher could find something.
On this basis, I'...