L_[NII]205/L_[CII] versus L_[OI]63/L_[CII] with the nine SPT DSFGs shown as yellow stars. The literature data are taken from FLAMES (Peng et al. 2025b), with references listed in Appendix A. As in Fig. 8, the SPT DSFGs are consistent with the literature counterparts in L_[NII]205/L_[CII], while they are offset in L_[OI]63/L_[CII]. The cyan crosses show the SPICE-simulated data (Sect. 4.4), which are slightly higher in L_[NII]205/L_[CII] than the observed SPT DFSGs, which may be a combination of over-predicted [C II] 158 μm and over-predicted [N II] 205 μm.