Eric Jager's book, which provides the source, is slightly more confusing than the screenplay, saying:
The prosecution and punishment of rape often depended on the victim’s social class and political clout. In France women convicted of lesser crimes like theft were often put to death, while many males guilty of rape escaped with a mere fine—compensation that was often paid not to the victim herself but to her father or husband, since rape counted less as sexual violence against a woman than as a property crime against her male guardian. Legal records show that clerics, men holding church office, numbered disproportionately among those accused of rape and that they often escaped serious punishment by claiming “benefit of clergy,” which entitled them to have their cases tried by the church rather than by the secular courts.
The circumstances of the crime, including the frequent absence of any witnesses, often made a charge of rape hard to prove in a court of law. And in France the female victim, no matter what her social standing, high or low, could not bring charges in the first place without the cooperation of her husband, father, or male guardian. Many rape victims, threatened afterward by their attackers with shame and dishonor, chose to keep silent rather than risk ruining their reputation, or that of their family, by making the crime public. So if in theory rape was a serious crime for which the law provided heavy penalties, in practice it often went unpunished, unprosecuted, and even unreported.
What work is Jager's "in theory" doing here? What is the nominal attitude on the books? Was it the case that it was de jure a crime against the woman but de facto treated as a crime against the man? Or was it de jure also a crime against the man for "violation of property"?
Moreover, was rape unique in that a woman was required to have her male guardian as a sponsor to bring the charge before the court, or was this a case with all criminal (or civil?) charges?
I don't entirely understand your confusion here. It's hard to overstate how unfair both legal and social attitudes toward rape have been historically in western society: marital rape was seen as an oxymoron, assaulted virgins were seen as having been awakened to ravenous sexuality, and yes, rape was seen as a crime against the man most shamed by the devaluing of the woman involved, whose honor was forever stained. This was a serious crime (it could ruin the reputation of the woman and her male guardian, and destroy the relationship between the men involved) but it was hard to prove (standards of proof were extremely high, a woman's word counted for very little) and therefore would often be dismissed or the victims would choose to never go forward in the first place.
One of the major barriers to a woman trying to prove that she had been raped in court was the unreasonable standard for her claim. The Sachsenspiegel, a 13th century lawbook from the Holy Roman Empire, for instance, required women who had been assaulted to report it immediately, while still disheveled from their trauma, and to literally shout for witnesses to prove her claim. In Philippe de Beaumanoir's 13th century French lawbook, Les Coutumes de Beauvaisis, victims of sexual assault likewise needed to prove that they had called out during the act, unless they were being threatened with death - and someone needed to hear them and attest to it. Then the judge could determine on his own whether her testimony was sufficient to merit the stiff punishment required by civil law - execution, which was assured for the rape of a married woman, and which could be transmuted into marriage for an unmarried one, as she would otherwise be unlikely to marry. (Clerical rape was hardly punished at all by ecclesiastical courts, on the other hand, and collective rapes were frequently committed by young churchmen from monasteries.)
Jager's "in theory" is recognizing that according to the law, rape could be punished with execution, but that there were social protections that prevented this from happening in reality, ranging from the protection given to clerics by canon courts to the difficulty of a woman to prove her assault if she didn't have anyone to be a witness in her favor. I regret that I cannot find the text of Beaumanoir's book to examine the specific wording, so I cannot say whether it's even described as being against a specific person - but that doesn't really seem to matter to me, given the context. It was certainly conceptualized as a crime against a husband, a father, a brother, or the men of an entire country or region. And when it comes to "sponsorship", again, I do not know the specifics of French law, but in medieval Europe single, widowed, and married women were typically represented by men in court; married women specifically were subject to coverture, a legal policy that essentially said wives were under the full guardianship of their husbands. I don't understand what relevance that has to the question, though.