Meir ben Borukh Rothenburg is in the Index under group R-A13358. Sample I13865 in the recently pre-printed Erfurt study (https://twitter.com/ShaiCarmi/status/1526850050772590592) is R-Y19847+, which means that the two lines are closely related on the R haplotree.
.I cannot say for sure how close, because the ancient sample provide only limited SNPs for classification. However, it could be very close. The only thing that prevents me from saying that I13565 is in fact the Maharam of Rothenburg is the fact that the latter is buried in Worms and I13865 is from Erfurt.
The date of I13865 is estimated to be anywhere from about 1275 CE to 1398 CE. The Maharam is believed to have been born circa 1215 CE and lived until 1293 CE. Rothenburg ob der Tauber is about 115 miles SW of Erfurt.