While a unit is buried in Graveyard, that unit is not in play; it's in a special Graveyard zone. It loses all properties such as attachments, +1/+1 runes, damage, etc. when it goes there. When you later play it from Graveyard, it will arrive and trigger any "arrive" effects at that time. — Sirlin
I would say they get stuck in that Graveyard zone.
But would be nice official words from