Electron spin echo envelope modulation (ESEEM) spectroscopy provides detailed information on electron-nuclear hyperfine interactions and has also been successfully applied to photoexcited triplet states. However, the interpretation of two-dimensional (2D) field-swept ESEEM patterns in disordered triplet systems remains challenging. In this study, we provide analytical and numerical descriptions of ESEEM in photoexcited triplet states (S = 1) within the high-field regime. We derive analytical expressions for the nuclear modulation frequencies and depths associated with individual electron paramagnetic resonance (EPR) transitions at specific resonance positions where the external magnetic field aligns with the principal axes of the ZFS tensor. At these positions, the ESEEM response simplifies and exhibits characteristic differences between the two allowed EPR transition branches, providing direct access to the sign of the ZFS parameter D and to the orientation of the hyperfine coupling tensor. Numerical simulations of 2D ESEEM spectra confirm the analytical predictions and demonstrate pronounced intensity asymmetries that depend on these parameters. The developed approach is applied to the analysis of 2D ESEEM experimental data for the photoexcited triplet state of the endohedral fullerene Y3N@C80, providing a consistent interpretation of hyperfine interactions involving both 89Y and 13C nuclei. The results establish 2D ESEEM as a powerful method for the characterization of photoexcited triplet states in polycrystalline samples.