[chrisism]

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I am guessing the above is not implimented yet as whenever i try and choose an artwork folder on a network share or usb stick it gives me and error when adding an emulator? if i choose an internal storage folder on the device it works fine.

Okay, I used to have SPMC just like you, but I switched to the official Kodi apk's with Jarvis. I am now running 16.2 with the official Kodi apk and that works fine for the Python version issue. Ofcourse you might find a way to update the python library within SPMC. Also koying already has a 16.4 version of SPMC as far as I know.
With the release of Krypton I am not sure yet for android since there is a whole deal with android development in the kodi team and koying went back to SPMC only.

Then with the whole path issue, with my setup I have a server with all my media. Kodi is using SMB paths to my shared folders. As Wintermute was saying I added a patch for SMB paths that fixes some issues for creating the asset folders dynamically. This is indeed not yet in the current releases. The usb path should actually work I think, I like to see logs of those errors, maybe we can fix that in time.

But the most important thing here is the fact that the emulator apps (like retroarch for example) dont support network paths on android!
If you want to run roms coming from a network drive/share you have to mount those, you cannot use SMB or other network paths. This could mean that you have to root you android to make this happen.
A different option is to use local folders, you have to check what folders your kodi can see. This can maybe be different with different android boxes, but check the Files/Folders explorer option in Kodi and map needed folders.

So in short with my setup I have all media on a server, Kodi itself (and thus AEL) uses SMB paths for all the assets (images/trailers etc). I have mounted the folders with my rom files and used the mounted paths as Rom paths in AEL.