The AVIC-RZ33 is a "hide-away" unit. The brain is mounted under a seat or in the trunk, while a motorized slide-out touch screen resides in the dashboard. This complexity makes language settings difficult to alter, as the system firmware is deeply integrated with the hardware.
This carries a risk of "bricking" the unit and is not recommended unless you are comfortable with system-level modifications. You can view a translated guide for similar models on ManualsLib Pioneer's official inquiry page for model-specific constraints. Firmware Updates: Pioneer Japan Support pioneer carrozzeria avic-rz33 japanese to english