Milestone 10/12 can be found inside a secret cave, where the Milestone 5/12 is located at its entrance. Inside, you should find 3 statues and near them the Milestone 10/12 can be found, here;
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1998627245

Milestone 8/12 is on the way to the Milestone 5/12 - near the big cable, here;
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2796983642
Following the path with the big cable you will come across the Milestone 9/12, here;
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2796988497
It can´t be missed.

Thanks, found them.