Comment 14 for bug 1565236

i created http://paste.ubuntu.com/16187883/ that at least gives you the AltGr keys in the terminal app (on a german kbd, other langs might have different needs indeed).

save it as /home/phablet/.config/com.ubuntu.terminal/Layouts/AltGrKeys.json on your device and you will have the keys in terminals "extra keys" selection.