Im currently working on my Witch/Alchemy themed tomb to share and I would like to add some elixir receipes, elixirs and spesific gems. I couldnt figure out how to do though, as debug items dorsnt contain books and stuff

Is it possible if my sims place them from inventory?

Wow EA did not like the idea of people passing out books in tombs. I tried a few variations including Ani's Shop from Inventory but it wouldn't let me toss in books into a chest when I didn't own the lot (everything else was available just fine and the chest could still be set up as a tomb object).
What I eventually got to work with books was to first set the lot to a residential lot and move someone in. That sim filled the chest (including with books). I then went to a different family, used Master Controller to force kill the sim who stocked the chest (leaving the house empty but the chests filled). Finally I changed the lot type to a tomb. My test sim was able to open the chest and take the books. I forgot to check if the books stayed in the chest if I further built on the tomb lot after swapping the lot type (but it should keep the chest stocked).

Wow, brilliant idea. Thanks, I will work on that. :D