The implication is that they are referring to the Lekgolo homeworld. The image in the Bestiarum in in fact a gas giant, not cloudy, rocky world. You are correct in that the word Te is not used.

: The Luminaries said, "Relics Ahoy!" but when they investigated they
: were disappointed to find Lekgolo huddled on the planet's rings. I read
: that as saying they checked out some readings and found little of
: interest. It was the readings that caught their attention - so they went
: to have a look see.

Yes, the fact that Forerunner metals and circuitry was present was enough to set off the Luminaries.

: If they evolved and weren't made in test tubes in an obliterated Forerunner
: installation then they would have had to evolve in a long lived
: environment capable of developing complex life forms. there would be an
: entire ecosystem with a long history.

They would have to have had a long-evolved history. One of the larger two moons of Te would be ideal if Svir V is in fact a gas giant.

: CH states that The icy rocks the made up the rings were in fact fragments
: of some obliterated Forerunner installation that once orbited the gas
: giant. That doesn't sound like a habitat that could have supported their
: evolution.

As above, there are two larger moons of Svir V and 23 smaller moons. This is not counting the Forerunner structure ring debris of Svir V (which Lekgolo can also survive in).

: How did they get there? Did they evolve on Te and travel to the rings under
: their own steam? (Lekgolo space program) Did the Forerunner take them to
: their installation as experimental subjects or as immigrants or as long
: term visitors/guests? Did the Forerunners make them and seed another
: planet in the system? (Te)

The Lekgolo go there under their own power (technology) long before Covenant contact. The Bestiarum states: "The High-G world made progress in space technology painfully slow for such an otherwise advanced culture."

: When did the Forerunner Installation (FI for short) go BOOM? Was it 100,000
: years ago? Were the Forerunners reseeding Te, had mostly finished and then
: their FI asploded leaving some Lekgolo survivors?

No info on this.

: If Lekgolo can live on icy rocky fragments then maybe they don't need an
: atmosphere. We know that they don't breathe oxygen but maybe they don't
: breathe period.

Perhaps. Respiration seems needed for life, but that's only Earth life for sure.

: I speculated that Lekgolo had a nuclear biology. An advantage of that is
: that they don't need to eat much to sustain their metabolism. They mostly
: eat to grow - they may be long lived and maybe they could have survived in
: the rings since the days of the breakup of the FI. maybe they spread via
: chance collisions. Could individual worms survive freezing? Or would
: internal radioactive heating keep them warm?

Nothing has mentioned Hunters are lethal to stand next to due to radiation. Not sure about this. You'd think they'd be more resilient to being squashed under boot like in Forward Unto Dawn.

: There could have been two populations of Lekgolo - those on the rings and
: those on Te. Maybe they evolved differences if they had a long separation.
: Maybe some of the ring populations have differences. They may not,
: necessarily, have become different species - there could have been smaller
: differences: size, coloration, tolerance to vacuum, etc.