Two thoughts about <mods:title>.

First, it seems there should be some standard way of dealing with initial
(non-filing) articles.  I can think of several alternatives:

1.a.  Make a content rule:  "Omit initial articles."
1.b.  Add a subelement <displayForm> as for <mods:name>, for the full
displaying form of title.

2.a.  Make a content rule: "Include initial articles."
2.b.  Add an attribute for the language of the title, so that applications
that care can strip initial articles when they have to.

3.  Add a subelement for initial articles.  E.g.
MODS test record example.

I mildly prefer 2 but it has the minor problem that the initial article
would not be available when converting from a 246 field.

Second, there are authority records for uniform titles, but there is no
"authority" attribute on <mods:title>.  Although there is (to my knowledge)
only one authority for them, it seems to me you might still want to provide
authority="naf" to indicate the uniform title was under authority and not
made up.  Also any other changes to MODS made for authority links for names
and subjects would be appropriate here.