At variance with the authors' statement [L. Pálová, P. Chandra and P. Coleman, Phys. Rev. B 79, 075101 ( 2009)], we show that the behavior of the universal scaling amplitude of the gap function in the phonon dispersion relation as a function of the dimensionality d, obtained within a self-consistent oneloop approach, is consistent with some previous analytical results obtained in the framework of the εexpansion in conjunction with the field theoretic renormalization group method [S. Sachdev, Phys. Rev. B 55, 142 (1997)] and the exact calculations corresponding to the spherical limit i.e. infinite number N of the components of the order parameter [H. Chamati. and N. S. Tonchev, J. Phys. A: Math. Gen. 33, 873 (2000)]. Furthermore we determine numerically the behavior of the "temporal" Casimir amplitude as a function of the dimensionality d between the lower and upper critical dimension and found a maximum at d = 2.9144. This is confirmed via an expansion near the upper dimension d = 3.