I added something important to the symbols plugin (it is a grapesjs plugin i created): you can now pause the syncing of a symbol and un-pause it later
Use case: a header on multiple pages, when you change 1 it updates all the instances. Now if you want one page to have a navigation element which is only on this page, you can turn off the sync, add the element and turn on the sync again
Also you can now "unlink" an element which means it will not be a symbol anymore
You can test it now. There are still issues with symbols, please check on github