NOTE: I use a dvorak layout keyboard and the qwerty '-' key maps to the '[' dvorak key.

While using the Schematic editor and dragging a part, the '[' key rotates the part as expected but also zooms out a fixed amount (same command as '-' key).

When a part isn't selected the '[' key still zooms out for me.

My guess is that this is related to using event.code vs event.key inconsistently (and perhaps against user expectations) in your event handlers for a keypress.