The other piece of brainstorming I know about, although I didn’t chase
all
the discussions in the devel mailing list, is the GSoC patch. This has
the
same goal of making it easier to coerce LilyPond into formatting chord
names
the way you want, but does so with a different approach: remember the
details
of how the chord was entered in \chordmode, so that the chord formatting
is closer to the input. Compared to just adding chord symbols with
\markup, that has the advantage that LilyPond understands what the
chords are actually made of, and the disadvantage that it can still be
cumbersome to teach LilyPond how to format the chords the way you
want.
I don't typeset chord names myself, I don't really know how strong the
arguments are for each side. Maybe there's a place for both, maybe not.
At any rate, as opposed to the chord semantics GSoC approach, it would
be rather straightforward implementation-wise to make LilyPond understand
arbitrary chord symbols, as shown in the code from my original reply.