That’s most likely an Android and/or Chromebook issue. The “Y” and “Z” characters will be swapped correctly in Dosbox (“Y” on the virtual keyboard will enter a “Z” character), but obviously, the swapping doesn’t translate well to your Chromebook’s keyboard.
You can remap these keys with Magic Dosbox’s built-in mapper tool though.
1. First, use Magic Dosbox’s onscreen keyboard to identify which key responds to which special character (for example “[” will type “ü”). Write these down somewhere.
2. Next, open Voodoo Control in Magic Dosbox. Tick the “Enabled” box below the “Mapper” heading.
3. Now comes the fun part. Tap “Gamepad Buttons” under “Joystick” (even though you’re not using a gamepad). Press the “+” icon.
4. Now, press the “ü” key on your Chromebook’s keyboard. In my case, it registers as a second “u” character (don’t ask me why ¯\_(ツ)_/¯).
5. Tap the “none” button to configure it, then “Key”, and select the “[” key from the list.
6. Confirm two times to get back to Dosbox.
Repeat that for every key that needs remapping. I’ve also recorded a little video of the mapping process: https://www.mediafire.com/file/20d5uup9vy929hg/MagicDosbox_key_remapping.mp4/file