Way to keep the walls from coming back in the Mine area

There is one room in particular that provides what you're looking for. You don't need to copy NPC dialog, though part of the fun is copying the other wall-writings for later consideration. So there is no single intended method (I imagine most people will look online)—your method could work, though it sounds frustrating.

Want a hint for that room's location?

It's off of the waterfall room.

Want an even bigger hint?

A pillar in the room links the code to an English pangram (sentence containing every letter of the alphabet).

And to give it away:

In the tree room above the waterfall, a fox jumps over a dog next to this pillar, which reads all the way around: "The quick brown fox jumps over the lazy dog." (image)

There are a couple of different types, each with a different solution. You'll figure them all out eventually, and doing so is part of the joy of the game, so I'll provide hints and the complete fix as spoilers.

The thick pillars with vertical glyphs on them: in the library/observatory area there's a room with one of these pillars and a part of the level that responds to your controller inputs.

The vertical glyphs are a line of tetris symbols on its side. Each symbol corresponds to a controller input: the 4 'T' blocks are cursor directions, the square is a jump, and the 'S' and 'Z' blocks are RT and LT respectively. Usually completing these gives an anti-cube, but sometimes they open a door.

The tall thin pillars with a square at the top: you need to be in new game+ before you can solve these. Once you're in NG+ try a different perspective.

Stand on the pillar and switch to first person mode, you should see a tetris symbols glyph nearby. Completing these gives an anti-cube.

The U shaped/tuning fork pillars: feel your controller - it's vibrating in a pattern.

The left and right sides of the controller vibrate the pattern you should repeat with LT and RT. Completing these gives an anti-cube.