I did another simulation for injection (-400 mm focal is not a common lens) and for the reflection (avoiding to change the already installed injection telescope into the homodyne).

The robustness for the injection telescope is really good, less than 3% moving the first lens in a range of +/- 5mm and less than 10% for the other one.

The robustness for the reflection telescope is not as good, we reach also 20% mismatch for +/- 5mm movement of one lens.