The official answer is 'No" because GarageBand is restricted in that way. It only lets you load sounds via the Library that are based on the ES2. You can see that if the ES2 is displayed in the Instrument Plugin Button in the Smart Controls (see screenshot below).
However, you can't open the ES2 Plugin Window (its interface) to make changes or load Plugin Settings that you have stored in MainStage or Logic Pro X.
However ...
There is some sort of workaround that lets you access Plugin Settings.
- In MainStage make the adjustment of the sound for the ES2 that you want to store.
- You won't save that sound as a Plugin Setting because GarageBand cannot access Plugin Settings.
- However, GarageBand can access Channel Strip Settings, so in MainStage, you click on the Setting Button on top of the Channel Strip that has the ES2 loaded and choose "Save as Channel Strip Setting".
- That Channel Strip Setting (I called mine ("ES - from MainStage") is saved in the following directory ~/Music/Audio Music Apps/Channel Strip Settings/Instruments/
- However, GarageBand only displays User Channel Strips that are located at the following location ~/Library/Application Support/GarageBand/Instrument Library/Track Settings/Software/
- You have to manually move (or copy) the Channel Strip Settings file ("ES - from MainStage") to that location.
- After that, open GarageBand, open the Library (Y), choose "User Channel Strip Setting" and you should see your Channel Strip Setting "ES - from MainStage".
- Click on it and GarageBand loads it to the current selected Instrument Track.
Keep in mind that this is a Channel Strip Setting, so it overwrites any other Plugins that you might have loaded on that Track.

Hope that helps
Edgar Rothermich - LogicProGEM.com
(Author of the "Graphically Enhanced Manuals")
http://DingDingMusic.com/Manuals/
'I may receive some form of compensation, financial or otherwise, from my recommendation or link.'