This ini file is a little old and gimmik-max-nnz is a GiMMiK configuration for the number of non zero entries that is longer supported.
Your error is most likely due to PyFR not being able to find a BLAS library. To understand more about the backends of PyFR this is a useful thread: What's the relationship between Gimmik and cublas?
Yes pyfrs and pyfrm file are in the HDF5 format. To quote the documentation:
To prevent situations where you have solutions files for unknown configurations, the contents of the
.inifile are added as an attribute to.pyfrsfiles. These files use the HDF5 format and can be straightforwardly probed with tools such as h5dump.