V = H1(mesh, order=order, dirichlet="bottom|right|top|left")
V.SetOrder(TRIG,1)

and

V = H1(mesh, order=order, orderinner=0, dirichlet="bottom|right|top|left")

should give the same result and I can just ignore the warning

WARNING: kwarg ‘orderinner’ is an undocumented flags option for class <class ‘ngsolve.comp.H1’>, maybe there is a typo?

A follow up question, if I explore the dofs using

for el in V.Elements(VOL):
print(type(el))
print (el.dofs)

I find whether I use V.SetOrder(TRIG,1) or V.SetOrder(TRIG,2), the same dofs are printed to screen. Is it correct to assume that although the dofs for V.SetOrder(TRIG,1) are printed to screen, they are not actually used?