I don't know if anyone is still interested in this, but I've managed to resolve it on my device.
I'm using a Samsung Galaxy 7, running Android 8.0.0. I downloaded an older version of PPSSPP, 1.6.3, set the Mode to Buffered Rendering, the Rendering Resolution to 1:1 and the Display Resolution to Auto. In the PPSSPP.ini file, I set FRAMEBUFEnabled = True.
No idea which part of that is relevant, but Danganronpa works fine for me now. All objects are detected properly by the crosshairs. There's occasional slowdown in the 3d sequences but that's it.
