You don't get there by splicing an ACE2 spike onto an RaTG13 backbone and passing it through a dozen mice. That gives you something that still looks similar to RaTG13 and infects mice.
The ACE2 spike also looks most similar to a previously unknown ACE2-binding spike protein found in malaysian pangolins.
So WIV would have had to have discovered that pangolin spike-protein, kept it secret, spliced it into an RaTG13 backbone, then not used mice but passed it through a species like that had a human-like ACE2 for a decade and millions of animals.
An alternative hypothesis is that Charles Darwin did that experiment.