> does it mean that in 1543 near Zurich this right was still being upheld
I don't know.
I am just saying:
(1) there are rennaissance and early modern authors who want to make us believe this was common and usual and happening widely during the 'dark ages' (likely from a mixture of anti-medieval sentiment and pornographic fantasy, but I am speculating).
(2) there are 20th Century and contemporary authors, who want to make us believe this was just a renaissance invention with no basis in fact whatsoever.
(3) given the available sources (like some religious texts, like the 1543 document I linked, like a very few other sources) and what we know about power dynamics and the 'justice system' (lol) in the European Middle Ages (there were very few limits on what a lord could do to local peasants without repercussions), probably neither is true.
(4) It likely happened, and it likely happened not just thrice over 1000 years. But it also wasn't something happening everywhere and all the time, and as a codified law. It wasn't "part of the package" of being a lord, with everyone just shrugging, saying "that's the way things are and ought to be".
(5) the idea of a culturally-homogeneous medieval Europe is laughable, before printing and modern-ish communication networks, customs were very likely more varied than they were in early modern times. The only (exaggeration!) trans-european force were the Catholic (which back then had a meaning of 'universal') church, and gold coins being accepted everywhere. So, except a few ways of trading goods and a standardized-ish Latin mass there were very few things true for all of the european Middle Ages.
(6) lords surely raped the peasant girls on their lands, and usually without any negative effect on the lord. That is the right way of putting it: rape. Even if there was (there very likely wasn't) such a 'law of the first night', it would still have been the same: rape.
These are my points, and they seem well supported by our current historical knowledge. For anything more specific, ask not just a historian, but a historian specializing in sexual relations in pre-modern Europe. I am not.