The paper reports on studies of the possibility of the transfer of the adjustable parameters of the line mixing model describing the v(3) absorption band shape of CH4 in helium to the case of the forbidden v(2) band shape. This transfer provides a reasonable overall agreement with the measured spectra, with deviations greater than the experimental uncertainties remaining in some J-manifolds. The model has been improved by taking into account the mixing of spectral lines with the same initial level. It was found that the description of the shapes of certain manifolds can be improved by fitting corresponding matrix elements of the optical rotational relaxation matrix, providing, in some particular cases, more detailed information on the matrix structure.