High-resolution incoherent scatter radar (ISR) observations of the E region electron density are customarily based on raw electron density, because accuracy of the high-resolution incoherent scatter spectra are typically insufficient for a full fit of plasma parameters using existing data analysis tools. Raw densities have also been used for electron precipitation energy spectrum inversion from ISR data. In this study, we use the Bayesian Filtering Module (BAFIM) to fit the true E region electron density, electron and ion temperatures, and ion velocity to ISR data with high resolutions in time and range, 4 s and 1.8 km correspondingly. We use the EISCAT UHF radar observation of an auroral event on March 09, 2016 over Tromsø. Both the raw electron density and the true one are then inverted into electron energy spectra using the ELSPEC software. Usage of true electron densities leads to wider electron energy spectra, auroral power up to 75% larger and upward field-aligned current up to 90% larger than usage of raw electron densities. The largest differences take place for precipitation activities which produce enhanced electron heating in the upper E region and in this study correspond to flux of electrons with peak energies from 3 to 5 keV. Finally, we compare the auroral power estimates calculated using BAFIM-ELSPEC analysis to the 427.8 nm auroral emission intensity (proportional to the total energy flux) and find a good agreement.