The MAX31790 is specified for a clock frequency from DC-400kHz, and SCL/SDA maximum rising time is 300ns (typ). The I2C standard specifies a maximum rise time of 1000ns.
The MAX31790 is rated for Standard and Fast I2C modes. The rise and fall time specifications in an official I2C document are 1000ns and 300ns max for standard and fast modes. It means that rise time should not be more than 1000ns for standard mode and 300ns for fast mode. The fast mode also has a minimum spec of rise time which is 20ns. Thus, the rise time can be anywhere from 0 to 1000ns for standard mode and from 20ns to 300ns for fast mode. The specification of rise time in the MAX31790 datasheet is just a typical value and the actual I2C specification holds.