Dear Marion,
Permit me to elaborate a bit on your interpretation
of the Duino Elegies. I wouldn't interpret the angels' world
as being furnished with Platonic ideals.  Rather I imagine the
angels' world as a world of unbounded, unlimited, hence chaotic
experience, the world in which Anaximander's apeiron reigns.
A species of Platonism, as I understand it, is implicit in Rilke's
account of "die Dinge", of "things" as the precipitate of experience.
As I understand Plato's ideas to be a reification of language,
so I understand Rilke's "Dinge" to be reifications of experience
in the sense of Erleben. For Rilke, "Dinge" are equivalent to
Platonic ideals, -in a less disciplined, less logical manner, but
humanly (psychologically) perhaps more profound. Plato as I read him,
was intoxicated with language, with words, and attributed to them
as his ideas or ideals, inordinate reality and virtue.
Rilke, on the other hand, is afflicted with an overabundance
of experience - Erleben - and the same fundamental psychic propensity
which leads Plato to postulate a world of "ideas" persuades Rilke
that temporal salvation is to be found by treating the "objects"
with which we are surrounded in a spiritual way; and to articulate
his vision, Rilke resorts to the simplest, most primitive use of
language - thereby denigrating the Platonic affinity for words, -
reducing experience to the perception of things, "Dinge",
and exalting "die Dinge" as the elemental precipitate of
our experience of this world. Does this make sense?