No Indian (and Bengali) keyboard layout in Ubuntu 17.04?
Solution 1:
The Bangla keyboard layouts seem to have been hidden intentionally in version 2.19 of the xkb-data package, which is the one shipped with Ubuntu 17.04. You know better than me whether the reasoning behind that measure is reasonable. (I'd be interested to hear your view.)
Anyway, they are hidden and not dropped. If you open a terminal window and run this command:
gsettings set org.gnome.desktop.input-sources show-all-sources true
the Bangla layouts should be shown in the user interface again.