That they don't works is half surprising.
Ren'py limitations regarding keyboard input on Android is supposed to regard entries that rely on completion. This imply that key
isn't explicitly said as not working (at least on the Android page of th e doc). But I guess this apply only to the effective text input, and that other kind of inputs are just disabled.
But that it don't works even with a physical keyboard is totally expected.
Ren'py will not start to investigate the system in order to know what kind of device(s) is or not connected to it. Either the keyboard input works, and it will works whatever the "keyboard" (physical, virtual, voice translation, etc), or the keyboard input don't works and, once again, this will apply whatever the "keyboard".