Not too sure what you mean - which part of the HUD is missing? Could you post a screenshot? Anyway, here's a couple of thoughts, however unlikely they sound:-
1) Is it possible the monitor just needs adjusting to display the whole screen in this mode, even though it works fine in other modes?
2) Maybe the patching process of the mods didn't work properly or, bearing in mind your earlier comments, something happened subsequently. If it were me, I would uninstall the widescreen mod and the game, ensuring the Baldurs Gate folder is removed as well, then re-install the game and mods from scratch. A bit of a pain, but you may find it is worth it .
As for the squashed menu, again it depends exactly what you mean, but if it is like the attached screenshot, then that is normal. The mods only affect the playing screen, not the menu screens. If you mean something else, then again, a screenshot may possibly suggest a cause.