Hello99 considers this the first of his main arguments:
“1) You have not mentioned a single name of a Rishon born in Germany before Rashi and the Baalei Tosafos, who were in France, to support your assumption that the community and Yeshivos in Germany preceded them.”
One of my acquaintances is presently working on a Memorbuch for Ashkenazic Jewry. That is, a Memorial book for all the communities in Ashkenaz that suffered persecution since the beginning of the settlement in Mainz until now. This work will also include, where available, a list of every rabbinic personality since Rabbeinu Moshe HaZakein ben Kalonymus of Lucca (who was brought to restart the Ashkenaz settlement in Mainz) until the present day.
Although this is hardly a comprehensive list, I will assemble a list of the Rabbinic personalities that preceded Rashi.
Rashi passed away in 4865, nine years after the massacres of the 1st Crusade.
Rashi learned by three great Rabbanim in Germany: Rabbeinu Yaakov ben Yakar (Worms), Rabbeinu Yitzchak ben Elazar HaLevi (Worms), and Rabbeinu Yitzchak ben Yehudah (Mainz).
These three Rabbanim all learned by the famous Rabbeinu Gershom ben Yehudah of Mainz. Rashi also learned by Rabbeinu Eliezer HaGadol ben Yitzchak of Worms and Mainz.
Rabbeinu Eliezer HaGadol ben Yitzchak learned by his relative Rabbeinu Shimon HaGadol ben Yitzchak, Rabbeinu Gershom ben Yehudah, and Rabbeinu Yehudah ben Meir HaKohen; all of whom were in Mainz.
Rabbeinu Yehudah ben Meir HaKohen himself was a disciple of Rabbeinu Gershom ben Yehudah.
Rabbeinu Shimon HaGadol ben Yitzchak is most famous for his Selichos and Krovos which are an integral part of our liturgy for the Yamim Noraim.
Rabbeinu Gershom ben Yehudah learned by Rabbeinu Yehudah ben Meir HaKohen HaZakein Leontin. He lived in the days of Rabbana Amnon (the author of Unesaneh Tokef), himself from Mainz.
Rabbeinu Shimon HaGadol’s grandfather was called Rabbeinu Abun HaGadol, and he was from Mainz as well.
This all points to well-established Torah academies in Germany, way before Rashi. If you can do the same for France, I would like to see the list.