Unnecessary, as I speak German.
The phrase quite unambiguosly means: doors of churches.
Apparently you did not read my translation above, since that is precisely what I wrote.
However, equally unambiguously, Roerer's annotation says absolutely nothing about physical documents being nailed to the doors of churches. It says that the "theses were made known at the doors of churches."
There are ways of expressing one's opinion at the door of a church other than physically nailing them.
Someone should have told Pope Leo. Article VII of the Papal Bull excommunicating Martin Luther ordered that it be published by nailing to church doors.
Interesting that you would make this claim, since the bull itself shows how unusual such a practice was. Let's look at what it says:
However, since it would be difficult to deliver the present missive, with its declarations and announcements, to Martin and the other declared excommunicates in person, because of the strength of their faction, our wish is that the public nailing of this missive on the doors of two cathedrals—either both metropolitan, or one cathedral and one metropolitan of the churches in the said Germany—by a messenger of ours in those places, shall have such binding force that Martin and the others we have declared shall be shown to be condemned at every point as decisively as if the missive had been personally made known and presented to them.
The Holy Father is saying that as unusual as it may be to nail this document on a church door, that is the only way - given the impossibility of physically delivering the letter to its intended recipients - to communicate its contents to the intended recipients.
Clearly hand delivery is the preferred method. The nailing of documents to churches is an extraordinary measure that has to be spelled out.
But, let's assume he Scotch taped the theses. The fact would remain that Luther did not consider the Theses to be a mere academic exercise; he sent a copy directly to Archbishop Mainz. The fact would also remain that the Archbishop knew of Tetzel's sale of indulgences for the sins of the dead and profited from it. Whether the Pope personally knew, the Vatican also profited.