I have a solar powered keyboard
An ML2032 is Manganese Dioxide based Litium Chemistry, whereas LIR2032 is traditional Lithium Ion.

The voltage difference may not be important to the Keyboard, but the fact they have vastly different charge and discharge curves most certainly will, since with a solar cell (how rare!?) the charging circuitry must be internal to the keyboard.

The ML2032 is full at 3.3-ish volts and empty at 2.0-ish volts. The LIR will not even be half full when charged to 3.3V, and will be much below its safest lower limit at 2.0V.