You do make a good point, I have to admit, and even if I say that they elected her after the other contender died in their war it would still need some wide explanations on why they would elect her seeing as she had male children (even if a late husband, her brother would have died when she was 37, she was by that point long married with children, including Rudolph IV).
I think in this case I'll need to admit something doesn't work and make that in the end of the succession war instead of her getting the throne her son is elected as emperor (even if he would have been a young teen by that point) while Maria Antonia remains as the ruler of the Hapsburg monarchy (or at least the Crownlands and Hungary), although I admit if (cof cof when cof cof) I do a follow up to this line, I'll probably have the empire become at least male-preference cognatic at some point in the 19th or early 20th centuries and more centralized in the sense of the power of the smaller states waning or being willingly lost to the emperor (which was a bit of what I was trying to indicate with the changes in imperial succession)
I must admit I also didn't really think about the other components of the HRE's government. But, in light of it, heres me trying to explain after thinking about it for a bit.
The reasoning I have behind the making of the position be de facto hereditary is/was, I admit, confusing, being based around the idea of the Hapsburgs managing to exert a larger influence over the empire due to coming out of the Thirty Years' War analogue with stronger base and through that managing to remain not only the nominal but de facto head honchos of the HRE and being capable of either convincing or forcing a large enough percentage of the empire's states to agree to their changes. About the other states exerting influence through their territories within the HRE (Britain through Fulda, Denmark through Schelswig-Holstein and France through Condé-held Strassbourg), my reasoning about them not getting involved on the changes in the law was that the Hapsburgs did it at a good moment as while France tried to sow chaos (and was the main backer of the uncle in the succession war) on the empire, both Britain and Denmark, which had influence through Fulda and Schelswig-Holstein, had close family ties to the Hapsburgs, with a British princess as Empress and Rudolph III's sister being married to the Danish king.
About the female inheritance, I never really understood why the germans didn't want women inheriting in any way shape or form (since in the end when their males ended they always were gobbled up by some other branch of the family, although short-sighted misoginy is probably the reason), but in this case I admit I may have done a large amount of mental gymnastics to make it work and it would need an impressive amount of explanation for that. The closest thing to an explanation I have is that Karl VI passed the change in the succession of the Hapsburg Monarchy (and not the empire, as he either considered it a given or didn't think about it) in a good moment and even then it was a close call on the Reichstag due to the reasons you mentioned above (reason why the uncle, which I'm going to call Ferdinand, had enough support to start a war over it later on), with the law also specifically mentioning that it would not have any correlation to the other states of the empire in the matter of their own succession (although many of her supporters would change their laws to semi-salic (or "if every single male in this family dies, then a woman can inherit") in the aftermath of the war).
Does that make sense to you? (It does to me, but...)
It does sound very snarky, but I get why you're being snarky, some things that I wrote sound extremely absurd without some explanation (or even with it)
