The present work builds on validation studies that compared results from the KORC model with both DIII-D and JET [1], where KORC evolves a distribution of REs due to guiding center orbits through spatiotemporal electromagnetic fields and collisions with partially ionized impurities. A significant finding of that work is the importance of the evolution of the spatiotemporal density profile due to impurity injection. In particular, including the neutral impurity species is critical for modeling to match experimental results, but only ad hoc profiles for the neutral impurities were available at the time. To address this need, time-dependent, experimentally inferred plasma and impurity profiles from the 1D diffusion model developed in Ref. [2] are included in the present study. A first effort employs 3D stochastic differential equations to evolve the momentum, pitch angle, and minor radius of REs to represent the transport coefficients, including the physics of partially ionized and neutral impurities for linearized Coulomb and large-angle collisions. This study develops algorithms optimized for computational efficiency and robustness for initializing the RE distribution and quantifying avalanche sources. Results indicate good agreement with RE plateau experiments and identify the importance of energy distribution in recovering the experimental current evolution in RE mitigation. Subsequent work uses results for plasma and impurity profiles from the 1D diffusion model in KORC. We compare the RE mitigation evolution and profiles from the previous ad hoc model to those using the 1D diffusion model. Additionally, we show that the avalanche source of secondary electrons, where the RE mitigation phase has several e-folding times, does not qualitatively change the macroscopic evolution due to the deconfinement losses of generated electrons. [1] M.T. Beidler, et al., IAEA FEC, Nice, France (Virtual) TH/P1-9 (2021) [2] E.M. Hollmann, et al., Nucl. Fusion, 59 106014 (2019).