Translation:I walk down the hallway.
In my experience, when we do use "corridor" in the US, it is usually for a larger public walkway, like in a building complex or a ship, whereas "hallways" are typically smaller, private spaces such as a family dwelling. Admittedly, "corridor" seems less common in several US regions.
So, does をin cases like this signify unidirectional movement? I'm not just aimlessly walking in the hall, but walking with a direction in mind? (Also, who uses hall to mean something other than a connecting space unless they are taking about academic buildings or being pompous?)
Unless otherwise specified, or if there are other exceptions stated, yes it refers to unidirectional movement, however, a different sentence would be used instead if someone were to loiter / linger aimlessly for example.
In a normal Japanese language lesson either online or offline or during a language test / exam like the JLPT, seldom there will be ambiguous situations, it is always going from point A to point B.
The path / route taken, either by foot, by any other means of transport, を is used to indicate place of transit, not the destination
教室に ろうかを 行きました I went to the classroom [ by the hallway / down the hallway ]
*hallway being the place where I pass through / pass by in order to reach the classroom
ろうかに 行きました I went to the hallway
*hallway being my destination, e.g. to meet someone there
The only difference I can think of is that walking "through" can sometimes mean that you are briefly passing through and then coming out of the hallway, whereas walking "down" is focusing more on currently being in the hallway and are not necessarily coming out of it yet. In practice though, "through" is often used the same way as "down" in this context, especially when there is no indication of where you're going to. For example, "I walked aimlessly through/down the hallway" vs. "I walked through the hallway and into the room".
Because that's not a correct translation of what the Japanese sentence says.
= walk the 廊下
= walk to the 廊下
に marks where you are walking to; を marks what is walked (a path, a route, a hallway, a park). You're not walking to the hallway; you're already walking in the hallway.
In English it has to be translated as "walk down the hallway" as we don't usually just say "walk the hallway". However, with some things we do just say walk on its own: "I will walk the Great Wall of China before I die."
Because peregrination is something you do over long distances, usually from one country to another; and a vestibule is not just any hall or corridor, but rather only between the interior and exterior doors of a building. "Peregrinate" would be most similar to 洋行する, while "vestibule" would be 玄関, 付室 or 前室.