Reliable interpretation of methane \(\Delta^{13}\mathrm{CH_3D}\){} and \(\Delta^{12}\mathrm{CH_2D_2}\){} requires the two mass-18 coordinates to be evaluated together with the absorption-window conditions that generate them. The research question addressed here is whether five measured mid-infrared transitions and twelve EP-reference gas entries can separate high-clump, low-clump, thermally heated, and hydrogen-rich methane states without reducing the classification to a single clumped coordinate. The transition records comprise \(^{12}\mathrm{CH_3D}\){}, \(^{12}\mathrm{CH_2D_2}\){}, \(^{13}\mathrm{CH_3D}\){}, \(^{12}\mathrm{CH_4}\){}, and \(^{13}\mathrm{CH_4}\){} lines, while the gas records comprise EP1, EP4, EP6, EP7, and EP6 heated at \SI{300}{\celsius}. The analysis calculates the local line-strength share of each target transition, consolidates reported gas coordinates with uncertainty weighting, and compares the resulting positions in paired \(\Delta^{13}\mathrm{CH_3D}\){}–\(\Delta^{12}\mathrm{CH_2D_2}\){} space. The \(^{12}\mathrm{CH_2D_2}\){} line contributes 1.10\% of the laser-1 line-strength total, whereas the \(^{13}\mathrm{CH_3D}\){} line contributes 11.29% of the laser-2 total. This spectral imbalance explains why \(\Delta^{12}\mathrm{CH_2D_2}\){} is a powerful but line-limited coordinate, while \(\Delta^{13}\mathrm{CH_3D}\){} has greater direct leverage but remains affected by neighboring methane absorptions. The calibrated gas positions separate EP6 and EP1 as high-clump references, EP7 as a lower-clump displaced gas, EP6-HG300 as a heated low-clump gas, and EP4 as a hydrogen-rich gas with \(\Delta^{12}\mathrm{CH_2D_2}\){} of 17.34\,\textperthousand{}. The main finding is that mid-infrared methane clumped-isotope calibration must preserve both mass-18 coordinates and report the local absorption-window structure supporting each coordinate.