>  Is this a bug with NetBSD curses also?

I think NO.

from initscr(3):

   The curses session must be initialised by calling initscr() which...
   This function call must be, with few exceptions, the first
   Curses library call made.  The exception to this rule is the
   newterm() call which may be called prior to initscr().

newterm() function is not called by aumix at all.

-- 
Best regards, Aleksey Cheusov.