Two-component LTE model for region 4 (in red) over-plotted to the rest-frame spectra (in black). The common velocity range (in km s⁻¹, after applying the radio convention and subtracting the v_LSR velocity of the region, as in Fig. 2, namely 252 km s⁻¹, see Table 1) is depicted at the bottom left panel while line frequencies are indicated above each panel in GHz and by green dashed lines inside the panels. Previous single-component LTE modeling (see Fig. 7) is shown in blue for comparison.