@Keule: Jou jemand Deutsches hier ^^
I'm now at day 22 and it works quite perfect.
I play the game with on german language but i can't say that the language matters... well at least not if you choose german or english.
I had really many crashes at the first few days. Everytime i tried to "dupe" stuff - the game crashes after a while.
But then i found a "way" to keep the stuff:
Everytime you "end" a day in the game, the game saves. So i activated the trainer - made me a lot of stuff. then i "end the day".
Then they are two options:
Option 1. The game crashes - you try it again
Option 2. It works and you have your stuff. Will the game crash after the "night" it doesnt matter, because the game saved "the beginning day" with your created stuff. Just start the game again, load and play with the created materials
PS: worked with every "multiplied" item ;-) lockpicks, diamonds, weapons etc.
What I also recognized is that the game dont like it when you cheat on Day 1 or 2 - at day 3 or more it works a lot better... dont know if this is only in my case.