I’m fairly sure this isn’t accurate. The rest of your post is, but you should be able to enter the post-medium-corruption Andras route without encountering the Jezera route, you just need for Alexia to have a low enough Jezera relationship score (and a high enough Andras score) before the first Andras event procs.
This is difficult because getting a high enough score with either of them by the time you reach medium corruption is very easy, but you should be able to by having Alexia avoid Jezera whenever given the option pre-medium-corruption—and maybe not putting her in the maid job, as well, though I’m not sure if that has any effect.
Not really sure why you’d want to go to the trouble, JezeraxAlexia is by far the superior NTR path.