α_[CII] vs. log Z for the SERRA galaxies (purple points, with inner white squares if they fall below the local KS relation) along with the best-fit linear regression ±1σ dispersion (purple line and shaded area). Lantana, Adenia, and Malva are plotted in blue, orange, and green, respectively. Previous derivations of α_[CII] in the literature are shown with shaded areas as follows: the green shaded area represents the Zanella et al. (2018) results (log α_[CII] = 1.5 with 0.3 dex dispersion over log(Z/Z_⊙)≈[−1, 0.0]); the yellow shaded area the Ramambason et al. (2024) results (converted into M_⊙ L_⊙⁻¹ units, over log(Z/Z_⊙)≈[−1.69, −0.3] range); the orange shaded area the Rizzo et al. (2021) results (log α_[CII] = [0.66, 1.3] assuming a fiducial range log(Z/Z_⊙)≈[−0.5, 0.0] for the dusty star-forming galaxies in the sample); and the pink shaded box the results from Kaasinen et al. (2024), who report α_[CII] = 4.6 ± 1.6× lower than Zanella et al. (2018), over log(Z/Z_⊙)≈[−0.3, 0.0] for the quasi-stellar objects in their sample. Cosmological and single cloud simulations (labeled “sim”) from Vizgan et al. (2022) and Gurman et al. (2024) are almost constant within their Z range, and are plotted in blue and gray, respectively. The α_[CII] − Z_⋆ relation from Casavecchia et al. (2025) is shown in brown.