I found a small bug in fe_abq.py:

HYPERELASTIC, REDUCED POLYNOMIAL with N=4 (8 constants)

When writing a HYPERELASTIC, REDUCED POLYNOMIAL material you need to have after the coefficients also the temperature, or omit it if not relevant.
 
If N=4, the first line is filled with 8 coefficients, so the temperature coefficient will go to the second line (max of 8 coefficients per line). If the temperature coefficient is omitted, an empty line should be left.

But in the current pyFormex code (or at least what I have on my laptop) the temperature is not written. Usually, this is not a problem (if N=1,2,3,5,6,7) but it is a problem if you have N = 4, because the temperature would require a new (empty) line.

This is the example on fe_abq.py:
    >>> intima = {
    ...      'name': 'intima',
    ...      'density': 0.1,
    ...      'elasticity':'hyperelastic',
    ...      'model':'reduced polynomial',
    ...      'constants': [6.79E-03, 5.40E-01, -1.11, 10.65, -7.27, 1.63, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
    ...      }
    >>> print(fmtMaterial(Attributes(intima)))
    *MATERIAL, NAME=intima
    *HYPERELASTIC, REDUCED POLYNOMIAL, N=6
    0.00679, 0.54, -1.11, 10.65, -7.27, 1.63, 0.0, 0.0
    0.0, 0.0, 0.0, 0.0
    *DENSITY
    0.1

This is correct because N=6 (temperature is omitted), but would fail with N=4, because the 8 constants would fill the entire line: [6.79E-03, 5.40E-01, -1.11, 10.65, -7.27, 1.63, 0.0, 0.0]