I'll try to address all of the issues you've described and explain as I go. First, you said a local audio file that is imported is not copied to the MS storage folder. This is absolutely not true. I just tested this on my Surface Pro 4, and the file was copied from the music directory in Windows 10 in the application storage directory. If you've changed your MobileSheets storage location, then you may be misunderstanding what is happening. If any file is imported from a subdirectory of the MobileSheets storage location, it will NOT be copied, because it doesn't need to be. So if you set the MobileSheets storage location to "C:", any file you import will not be moved, as you've specified the entire C drive as your storage location (this would obviously be a pretty extreme thing to do). Likewise, if you use C:\MyLibrary, and then import an audio file from C:\MyLibrary\MyAudio, that file is going to remain in that folder. If you backup your library and restore it on another machine, it will restore the audio file to whatever storage location that device has selected without trying to restore the folder structure. This is something I can improve on, and will make a note to do so in a future update.
If you import through the companion application, you have two options for the destination. The first is the "Music" directory in Windows, which is a shared directory that isn't removed if you uninstall MobileSheets. The second option is the storage location. I've tested both optoins, they both worked for me, and I didn't encounter any disruptions of the sync connection. If you did, please let know which option caused a problem. If it's the music directory, I'll need more details on what device you are testing on, and any possible explanation for why MobileSheets was not allowed to write to the Music directory.
It is true that you could spread your files between the music folder and the storage location, but I don't believe it should be possible to have them spread over other locations. This is only true of the Windows 10 version though, as the Android version gives users more control over where their files are stored. If you are finding it possible to add an audio file and it isn't copied to the storage location and it also isn't in a subdirectory of the storage location, I'm going to need more details on how to reproduce this problem.
So in summary, I don't think the handling of audio files is a mess, but it's possible you are seeing different behavior on whatever device you are running on. I'm testing on a Surface Pro 4, which is currently the most widely used device among MobileSheets users. I've also tested on my PC, and didn't encounter any errors there. I will try to improve how folders are restored when restoring a backup file, but in theory, every audio file should be extracted to the storage location root folder. If you are not seeing this happen, then I will have to run some more tests and I may need additional information from you, because I don't recall seeing that in any of my previous tests.
I can look into trying to send audio files to other applications for playback, but I doubt this will work very well. There won't be any tight integration between MobileSheets and the external audio application, and I can't just send a file directly to another application to play. I can tell Windows to load the file, and if you've set a default application, it should in theory just use that one. It will also bring that application to the foreground though, so you would be taken out of MobileSheets and forced to switch back. I don't believe there is any way to avoid that, but I can look into it some more. I've found a solution on Android to allow changing audio speed playback and pitch, but I haven't found a solution on Windows 10 yet for UWP. There seem to be no open source or commercial libraries available to support this in a C# UWP application.
Mike
If you import through the companion application, you have two options for the destination. The first is the "Music" directory in Windows, which is a shared directory that isn't removed if you uninstall MobileSheets. The second option is the storage location. I've tested both optoins, they both worked for me, and I didn't encounter any disruptions of the sync connection. If you did, please let know which option caused a problem. If it's the music directory, I'll need more details on what device you are testing on, and any possible explanation for why MobileSheets was not allowed to write to the Music directory.
It is true that you could spread your files between the music folder and the storage location, but I don't believe it should be possible to have them spread over other locations. This is only true of the Windows 10 version though, as the Android version gives users more control over where their files are stored. If you are finding it possible to add an audio file and it isn't copied to the storage location and it also isn't in a subdirectory of the storage location, I'm going to need more details on how to reproduce this problem.
So in summary, I don't think the handling of audio files is a mess, but it's possible you are seeing different behavior on whatever device you are running on. I'm testing on a Surface Pro 4, which is currently the most widely used device among MobileSheets users. I've also tested on my PC, and didn't encounter any errors there. I will try to improve how folders are restored when restoring a backup file, but in theory, every audio file should be extracted to the storage location root folder. If you are not seeing this happen, then I will have to run some more tests and I may need additional information from you, because I don't recall seeing that in any of my previous tests.
I can look into trying to send audio files to other applications for playback, but I doubt this will work very well. There won't be any tight integration between MobileSheets and the external audio application, and I can't just send a file directly to another application to play. I can tell Windows to load the file, and if you've set a default application, it should in theory just use that one. It will also bring that application to the foreground though, so you would be taken out of MobileSheets and forced to switch back. I don't believe there is any way to avoid that, but I can look into it some more. I've found a solution on Android to allow changing audio speed playback and pitch, but I haven't found a solution on Windows 10 yet for UWP. There seem to be no open source or commercial libraries available to support this in a C# UWP application.
Mike