I realise I am replying to a very old post, but I have actually found a great way to control the Android Bandhelper app using Cantabile!
My setup is based on the following two things:
- a Yamaha MD-BT01 wireless midi adapter (purchased for €42 and received this in the post this morning)
- the Bandhelper app (solo version costs $12 per year but the first month is a free, no-commitments trial)
Installing and configuring the MD-BT01 was very easy. I connected the MD-BT01 to the midi input and output ports of my Arturia keylab mkii and then opened the Bandhelper app to pair with the MD-BT01 from within the app itself (this is what I recommend doing, because when I tried pairing the device in the tablet’s Bluetooth settings, Bandhelper wouldn’t recognize it).
I now have fully automated control over my lyrics through Cantabile. No more touching the tablet screen or using a Bluetooth foot pedal! Bandhelper automatically switches to the next song on the setlist as soon as I move to the next song in Cantabile, and it starts showing the right lyrics (or section thereof) as soon as I start the song in Cantabile and as the song progresses. So far, I have been using Setlist Helper on Android for my lyrics and still like that app for its simplicity, but it does not support midi over Bluetooth, so the switch had to be made…
Bandhelper can receive and send all kinds of midi information (including note messages, cc messages and sysex messages) and so is extremely flexible to work with. It’s also quite feature-rich (way more features than I will probably ever use) and has a bit of a learning curve, but nothing a Cantabile user can’t handle 
I set up Bandhelper to send and receive on midi channel 16 and assigned cc numbers to specific actions (play, stop, scroll down, etc.). Then, I first created bindings in my background rack to general actions like start/stop song and previous/next song in setlist. And after that, I added transport position bindings in each song to make the lyrics in Bandhelper jump to the relevant lyric parts. Everything works as expected.
Bandhelper let’s you assign a program change number (Bank MSB, Bank LSB, Program) to each song, so this is what I did. Then, I added a binding to each song for Song > On Load to automatically open the lyrics of a song as soon as I open the song in Cantabile. Now, even if I scrolled through the setlist in Bandhelper, it will still jump to the right song as soon as I press the Next Song button on my controller keyboard (I have Cantabile invoke the Song > On Load binding with a 120ms delay, so as to allow Bandhelper scroll to the next song first (based on the Nest Song binding in the background rack), and then receive the Program Change (Banked) message from Cantabile to open the correct lyrics. This is making me so happy 
Incidentally, a very nice feature of Bandhelper is that it let’s you record an automation track. This works very much like a macro recorder and records everything you do, such as pausing and resuming the scrolling at certain points of a song, or jumping to a specific verse or chorus (the app supports song position tags), at exactly the right moment. However, I think I prefer the use of bindings to song positions in Cantabile to control the scrolling/jumping/pausing/resuming. This way, automation is done in Cantabile and only the lyrics are done in Bandhelper.