If you make the output of the I2C level shifters "3.3V SDA" and "3.3V SCL", en then connect both sensors to the 3.3V I2C bus, then you need only two mosfets.
With a I2C level shifter, there is a 5V I2C bus and a 3.3V I2C bus.
All 5V sensors can be connected to the 5V I2C bus.
All 3.3V sensors can be connected to the 3.3V I2C bus.
Please tie the inputs of the unused ports of the HC4050 to GND.
The RX an TX are still shortcut/clipped by the leds.
Where is the 3.3V voltage regulator for VCC ?
If have not checked all the connections of each sensor and chips. For example the pins that are set high and low, sometimes with a resistor.