multiple diode problem computer simulation and hand answer don't match
Your diode states are correct. That being said diodes are complex non linear components. The exponential model is the best tool to get the perfect result but mathematically it is difficult to apply for circuit analysis. The constant voltage drop model is meant so simplify this calculation but it won't give you the perfect results. The simulation model is capable of doing the complex calculations of the exponential model and provides a more accurate answer.