According to the TWI sections of the documentation here and here the TWI baud rate is variable through the whole range of 0Hz - 1 MHz. The implementation of the Wire library for the megaavr however explicitly hides that functionality in a hidden way.
I suggest removing the code that limits the baudrate to the 3 distinct values defined in the Philips I2C standard in order to be able to communicate with devices that do not match that standard.
According to the TWI sections of the documentation here and here the TWI baud rate is variable through the whole range of 0Hz - 1 MHz. The implementation of the Wire library for the megaavr however explicitly hides that functionality in a hidden way.
I suggest removing the code that limits the baudrate to the 3 distinct values defined in the Philips I2C standard in order to be able to communicate with devices that do not match that standard.