Thanks for this great info collection
Some weird thoughts about Calderius in the replies - Cyborg/Robot is the platform, I guess he (the ghost) was Jennerit/race under Jennerit control before. I don´t really see why it matters if his new body/platform is a robot or a cyborg…
The first thing Caldarius reminded me about was the Prometheans from Halo4 - human souls uploaded and sustained in robot like bodys from alien-alloys and hardlight.
My guess: uploading a ghost into a robot/cyborg host in a widespread tech within the Battleborn Universe (see ISIC?) and within the Jennerit empire its handled as an award, as you already said. The worthy become sustained, their ghost becomes immortal.
(btw. ISIC could of course be a true AI, its just a thought)
I love to think of the Jennerit as a Type-II race on the Kardashev-scale, which means they are able to use all energy produced by their (sacred) central star.
wiki -> https://en.wikipedia.org/wiki/Kardashev_scale
On the artworks showing the Solus system we can see a giant red dwarf star surrounded by red light shards “howering” over the Jennerit homeworld. For me it seems they converted their sun into a movable reactor - no wonder they have Sun priests and a sun cult + highly advanced knowledge about light (lasers, hardlight,ect…)
I guess their own converted red dwarf star is not enough so they may harvest other stars.
As such a high evolved race its only understandable to become a bit megalomaniac and selfcentered, and in this manor it could explain why Rendain is so confident in his idea to work with the Valresi.
(love that. His overconfidence is his weakness. Oldschool but always working^^)
additional point: The Valresi could be a Type-IV civilisation, harvesting the entire universe.