I am in SERIOUS trouble! [KCD2]

I am in serious trouble because I stole the old painted statuette before the German treasure quest. Now I'm stuck on that quest because, despite having the item, the game won't progress unless I steal from the chest. And since it is a quest item neither I can transfer nor drop it in order to take it back again from the same chest. I took that item a long time ago, so loading a save where I didn't take it means I'll have to complete a lot of quests again. Furthermore, I tried to use cheat mod to remove it from my inventory and re-add it, but it failed even with the correct ID.