Here's How to download, install and view Rosetta Stone - the zip file.
Rosetta Stone
http://www.carls-sims-4-guide.com/forum/index.php/topic,19724.0.html1. Download Sim, and go to the folder you downloaded the file to and unzip it by clicking the file and select extract here - using your zip file program.
2. It will unzip as a .package file.
3. Copy the Rosetta Stone.package file to:
----> C:\Users\<Username>\Documents\Electronic Arts\The Sims 3\Library
** This puts the sim in the Household Library.
4. Load game, and find her in the Household Library. - It's the "Solid House" Tab.
** Note:** - Her icon in the household library may come up blank. - Due to her photo not being cached. So you will need to search for her, or just look for a blank thumbnail. It's most likely to be Rosetta. Mouse over the blank thumbnail, it should show her last name - Stone.
She does show up in game after you place her to play. To fix this, re-save her to the household library.