The tablets are RNG but, on one of the early days where you can start getting them from the valley, you can 'roll' a different tablet if you hit the back button a few lines. Once you get a tablet, it will permanently be unlocked in the main menu's files section, even if you rewind the conversation to roll again. You can just keep doing that until you get the achievement to pop, then go to the menu to read them.
😊
This seems to stop working once you have your Office. I believe the random seed for determining what you find in the valley seems to be set before or as you click "Confirm Plan", which you cannot then use the back button to move past.
Mind you, the tablets are the most numerous collection, the transcripts should only have 6 to find in the valley (Poseidon and Athena are being saved for later builds, 2 gods totally abstained (IIRC devs implied they won't get a transcript because of this), and you get 5 guaranteed transcripts from Argos it seems) and that feels reasonable to not have this easy reroll scumming to get.