Take:

header yy
{
  bit tt;
}
struct y
{
  yy[2] tt;
}
header t<tt>
{
  tt y;
}

typedef t ty;
typedef ty<y> tty;

Right now the compiler outputs:

t2.p4(11): [--Werror=type-error] error: Field 'y' of 'header t' cannot have type 'struct y'
  tt y;
     ^
t2.p4(5)
struct y
       ^

But it does not reference the last typedef line for the subsitution that had happened so it is not obvious where the problem is located.
I suspect this is an issue with most places of subsitutions too include functions.