hi, the burial mounds are in chapter3 not chapter2. one starts in the deep forest, one in the barn, and one in the laboratory.
it will be easier for you to ask questions in the discord server, the link is right below the patreon link.
The game wont run if its missing chapters. try to merge all your chapters again. if you dont have chapter4 merged then its possible that you encountered a bug that let you continue to chapter3 after dying in chapter2 instead of ending your game. just replay from the end of chapter1 and make sure not to die.