From what I understand about synced sharepoint folders, they allow users to continue working on files in its folder even if the internet is down. Therefore, internet connectivity shouldnt be an issue. Furthermore, only one user should be editing the unique front end accde file anyway. Therefore, there should not be any clashes with data. Also, when I said update over the internet, I meant periodic updates to the design of the front end for me to push to the users. With the synced sharepoint folder, all I have to do is schedule down time with the client then drag and drop the new front end file into their respective folder. This literally takes 5 seconds to do.
@The_Doc_Man I want to ensure I understand your concerns as I can tell you understand access/database design a whole lot better than I do.
This link kinda sums up what took place with my application:
https://sharepointmaven.com/how-onedrive-sync-works/