Norwegian keyboard layout wrong; AltGr not recognized

[ltning]

When using the Norwegian/Norwegian Extended keyboard layouts, several key mappings are wrong:

• < and > are located at the top-left key (above TAB), rather than next to LSHIFT as expected
• AltGr does not seem to do anything; e.g. AltGr + 2 should give @, but does not. Similarly, AltGr + ^~¨ should enter accent mode and subsequent space should give ~, a should give ã, etc.

What other information can I provide to help? I would assume German layouts facing the same issue; if they have been fixed there, the same fixes may work here?

[ltning]

Update: Having learned that ctrl+alt is roughly equivalent to AltGr (in GEOS), checking the corresponding box in the keyboard settings does solve the @-problem (and some similar ones).
However, the < and > are still in the wrong place - but on a different key than reported: They are mapped to the rightmost key in the middle row of characters (asd....øå.). This should have ' and *. Additionally, the ø seems to be a dead key (to the right of L).

Keyboard layouts are complicated. :D