Offsets of spectral indices measured from the wideband MTMFS images with respect to spectral indices derived from processing the full bandwidth using 15 individual SPW images from Deka et al. (2022) as a function of flux density. The spectral indices are calculated by using the SPW2 and SPW9 images. Binned median offsets are shown (blue), along with the offsets without the correction applied in Sect. 4.1 (red), showing that the spectral indices are properly corrected.