Maybe @w@ sorry but I think this is a compatability issue, and shouldn't your keyboard goes into "Pop up" mode? .3.a
for my phone it will drag the screen text box upward so i still can see what i write but usually it's will came down again afterwards, but for the vn from renpy sometimes it will stuck like that, but yeah it's maybe just compatibility issues, it's not a big problem though since i can fix it with just click home button and open it again or just use safe files, but it's may be a little annoying if there is more thing to write in the game for the next update lol, but afterall i still love your vn though so don't worry about it.