There is certainly no problem in using a single shared 'jbcore' folder for all your galleries (please see the Using an External jbcore Folder support section for details) and if you are seeing the "Config file not found." message, then the path to your 'juicebox.js' file (within the 'jbcore' folder) is correct.
If you are using a baseUrl, then the baseUrl entry should point towards a complete gallery folder.
The gallery's configuration file should be named 'config.xml' (its default name) and should be located directly within the gallery folder (its default location).
If you change the name of the configuration file or move it, then you can point towards it with a configUrl entry in your gallery's embedding code (please see the Embed Options section of the Config Options page).
However, a configUrl should not be necessary unless you want to manually change the structure of the gallery (or rename the configuration file).
Just make sure that your 'config.xml' files are inside your gallery folders (where they should be if you created your galleries with JuiceboxBuilder-Lite) and that your baseUrl entries point towards your gallery folders.
The baseUrl entries can be relative paths (relative to the web page containing the embedding code) or absolute paths (in the form 'http://www.example.com/gallery_folder/'.
At the moment, your baseUrl entries are relative paths and your 'ValleyForge2017' and 'Germantown201' gallery folders should be located in the same directory as the web page whose HTML code you posted.
After creating your galleries with JuiceboxBuilder-Lite (and saving each one to its own individual folder), there is no need to modify the gallery folders at all.
Just upload them to your web server and make sure that the baseUrl paths are correct.
For reference, the baseUrl method of embedding is documented here.
General information about the "Config file not found." message can be found in this FAQ:
When I view my gallery I see the message 'Config file not found'. How do I fix this?
Incidentally, if you encounter the "Config file not found." message whilst trying to view a gallery locally (from your computer rather than from your web server) in Safari 11, then please see this forum post for a full explanation and a workaround.
Unfortunately, Safari 11 (released 19 September 2017) introduced a new security restriction which prevents local viewing of Juicebox galleries by default. This issue is specific to viewing galleries locally (from your computer's hard drive) and there is no such issue once the galleries have been uploaded to a web server (where they can be viewed in any modern browser).
Selecting 'Disable Local File Restrictions' from Safari 11's 'Develop' menu (full instructions in the link above) should, once again, allow you to view your galleries locally in Safari 11.
I hope this helps.
However, if you continue to experience difficulties, then please post the URL to your web page so that I can take a look at the problem and help further.