The PIONEER experiment aims to measure the 10^-4 charged pion branching ratio, (π→e)/(π→μ), to an unprecedented 10^-4 precision by measuring the final-state positrons from each decay type. A key discriminant between the two decays is the positron energy, but energy-dependent physics effects introduce biases in trigger efficiency and fiducial acceptance. This talk will present strategies under development to correct for these biases, as well as reconstruction efforts designed to minimize their impact on our measurement.