I have checked SDK examples and do not find any place where those registers are set :
__IO uint8_t SLTH; /**< I2C SCL Low Timeout Register High, offset: 0xA */
__IO uint8_t SLTL; /**< I2C SCL Low Timeout Register Low, offset: 0xB */
It means by default timeout has infinite value ?
In what units those registers should be programmed ? Period of clock 400kHz or some other ones ?