Updated information for IMO is available here <https://www.cypress.com/documentation/code-examples/ce219322-psoc-3-and-psoc-5lp-internal-main-oscillator-trim>
From the family datasheets ILO accuracy for 24 MHz - non-USB mode is +/- 4%..
Accuracy for 24 MHz USB mode with oscillator locking to USB bus is +/- 0.25%.
I see now AN80248 is indeed replaced by 002-19322 (=CE219322)
Thanks for this answer.
Yes, the 24MHz USB mode with the oscillator locking to the USB can achieve +/- 0.25% accuracy. But this assumes the USB is connected to the PC and the PC is providing a 48MHz reference clock from its USB. If the USB is disconnected or the PC is powered down and the power to the PSoC is not via USB, then the external reference clock is missing and the IMO will at best favor a +/- 4% tolerance. Maybe someone from Cypress can weigh in on this.