Spiral arm models from Levine et al. (2006) (HI regions), Hou & Han (2014) (using only HII regions or three different tracers), Sun et al. (2024) (CO regions), and Drimmel et al. (2025) (DCEPs) are superimposed on our targets in the top left, top middle, top right, bottom left and bottom middle panels, respectively. All the models (with the exception of Sun et al. 2024) are collected in the Python SpiralMap package (Prusty & Khanna 2025). Spiral arm colours are the same as those in Fig. 7.