In my brief test, this still appears to be a problem.
FM GO 13.03, iOS 7.1
FileMaker, Inc. has identified an issue when trying to use a URL to open a locally stored file on an iOS device that is running iOS 6. For example, say you are trying to open a file called "Assets.fmp12" that is stored locally on your iOS device by typing in the following into Safari:
When attempting to open the file shown using the url syntax above, you might receive an error message similar to the following:
"Safari cannot open the page because it is a local file"
FileMaker, Inc. is aware of this issue with the FileMaker products listed.