I'm not sure that the search engine looks for files in half private folders like the ones in Library folder. That's the reason why I proposed to use Go > Go To Folder menu item in my answer to the thread Where are settings (textures, 3D models, etc.) saved on the Mac?
So, open a new window in the Finder, select Go > Go To Folder menu item (cmd + Shift + G shortcut) and enter the folder ~/Library/Application Support/eTeks/Sweet Home 3D (with the ~ leading character and the spaces in Application Support and Sweet Home 3D).
Open another window in the Finder, select Go > Go To Folder menu item and this time, enter the folder ~/Library/Containers/com.eteks.sweethome3d.SweetHome3D/Data/Library/Application Support/eTeks/Sweet Home 3D.
Finally, copy / paste the files found in the folder ~/Library/Application Support/eTeks/Sweet Home 3D into the folder ~/Library/Containers/com.eteks.sweethome3d.SweetHome3D/Data/Library/Application Support/eTeks/Sweet Home 3D.