Here are some things to try.

1
delete the complete playlist, trash the songs and empty the trash. In the Playlists window, swipe from right to left on the playlist name (Latin 50), tap Delete, choose Move all songs to Trash, Tap the Trash, at the bottom of the window, Empty trash.
Then go to forums and import the playlist again.
Run the send and import tests again.

2
force quit iReal Pro and open it again, then send the 11 y 6 song again (or any other faulty song) via email and see what happens.

3
force quit then turn off your iPad completely then turn on again. Then email the song again.

4
are you able to try a different email address (do you have another set up on your iPad)?
are you using the default Mail app on the iPad or another?

5
I need to see the faulty song in forums, tap on the Send icon as usual, choose Forums, log in then post it in a new thread in our Sandbox.
Also you can see what happens if you tap on it to import. Does it come up with an error?
To be sure you can upload to forums, you could try with a song that you know is ok (on import) and test in the sandbox it imports ok again, then do this with the faulty song.

6
the other thing you could try is to make a backup and delete the app, download again from the app store, then import your backup. The forum playlists can be downloaded again, but if you have personal songs, you should check that they are all importing ok before you delete the app. If they are faulty then we will have to look into this before you delete the app - so do not do this yet.

Sorry for the problems.
Thanks, post back in this thread.