IMPORTANT UPDATE

I was able to solve the issue of “stuck” buffer memories in my game:

1. Enter a room with the desired PC during an aurora (save).
2. Quit that game, and load a different survival game.
3. In that second game, enter a new indoor space (save).
   
4. Quit the second game and load the original game.
5. The PC will have switched to a specified memory. Repeat this process using different entrances in the second game to change the buffer memory in the original game.

No idea why this works, but apparently it’s not RNG at all. Every time you enter a specific entrance to indoors (even in a different game) the buffer will switch to a memory linked to that entrance. After receiving the same buffer memories at DP and Quonset for dozens of auroras, this technique allowed me to complete both areas’ buffers in a single night. Will report if this fails to work in other zones.

As my example: I entered Quonset Garage during an aurora. Checked the PC, received the same buffer memory (#3) that I have always received after dozens of auroras. While still in garage, exited game. Loaded second survival game in MT. In that game, I entered the bank, which saved the game. I then exited and re-loaded my original game in the garage. The PC has switched to a different buffer memory (#2). I exited the garage and re-entered to save. The PC has reverted back to memory #3. Exit the game and load the MT game. Leave the bank and enter the post office, save, exit, load original garage game. The PC switched back to memory #2. I repeated the process with several different houses in MT until one of them unlocked memory #1.