Ways to talk about nostagia
Traditionally, Mandalorians don't succumb to "a bittersweet yearning for the things of the past"; they are a present-focused people. The closest their culture comes to that yearning for the past is encompassed by aay'han, a moment of both mourning the dead and celebrating the living.
Nonetheless, while most Mandalorians are taught to be present-focused, some could still get caught in the past because of a tragedy. Because it would be rare, though, the culture wouldn't create a special word for it. But it's still possible to describe something like "death by nostalgia" even with the words we have. For example:
Or'copaad ti ruyot kyr'amu kaysh. An obsession with the past kills/killed them.
Ibac adat echoyli par ruyot. That person grieves for the past.