Does Rashta die?
As she dies, Rashta hallucinates Navier embracing her like she did Lebetti, further suggesting she genuinely looked up to her and wanted her friendship. Also, Heinly: yes, he genuinely loves Navier and acts like a lovesick puppy around her.
What happens to Rashta?
Sovieshu quickly took Rashta as a concubine and eventually divorced his wife, Navier, to marry her so the child she was pregnant with would become a prince/princess. Despite knowing his intentions, Rashta was convinced she would remain as Empress and would happily live with Sovieshu and Glorym in the palace.