ippeveprinter (2.4.2) does not allow for any pagesize tolerance.
I'm not sure whether IPP standard allows for any.
The relevant code is (ippeveprinter.c:8779)

      for (i = 0; i < count ; i ++)
      {
        size  = ippGetCollection(supported, i);
        x_dim = ippFindAttribute(size, "x-dimension", IPP_TAG_ZERO);
        y_dim = ippFindAttribute(size, "y-dimension", IPP_TAG_ZERO);

        if (ippContainsInteger(x_dim, x_value) && ippContainsInteger(y_dim, y_value))
          break;
      }

The problem comes from the fact that IPP specifies page size in 0.01mm units,
while PPDs usually in integer postscript points (1/72 inch). The conversion between the two
may introduce small offset, and a print job submitted to ippeveprinter may
be rejected during verify phase.

The quick&dirty (very little testing done) patch below implements
more robust conversion algorithm, which seems to work for me
for a couple of printers/PPDs.

cups-2.4.2-pspoints.patch.txt

However, I think better approach would be to allow for some page size tolerance,
i.e. via command line option. The default could be zero for compatibility.

On a side note, the patch also improves handling of IPP_TAG_ENUM options.
Without it, conversion of enums to integer gives often zero (again very little
testing done).