If we look more closely at the surviving photograph of the baptismal font with four puttos that was in the baptistery and the figures and ornamentation adorning the font’s cupola, Ackermann’s authorship becomes dubious: the cutting line appears to be too soft even compared to Ackermann’s early works, and the treatment of the figures in terms of body postures, faces and garment details differs from the master’s other works.

The figures depicted on the lid of the baptismal font – Christ as Salvator Mundi, the apostles, Christ being baptised by St. John the Baptist, and the statue of a pelican – do not resemble other corresponding figures fashioned by Ackermann. There are no details in these works that repeat elsewhere, and their cutting lines do not resemble Ackermann’s style either. Their cutting lines appear to be too soft in comparison to other works. The treatment of the figures in terms of body posture, faces, and clothing details differs to too great a degree from the master’s other works.