Okay, so I'm my sburb play Astrid never lived on Alternia, as if takes place after the Canon sburb plays. Troll DNA and coding had traveled through a many of different universes, many being unstable and glitchy, the troll the finding herself on a planet inhabiting humans who had found their way into another universe as well, surviving the end of the world. Limebloods coding still had existed it was just torn for quite a while, so she, and many other of her caste existed in the same planet with said humans. The reason she is able to talk to trolls existing in Alternia is because of Fern's time shenanigans, every once in a while in comic we see the human ducking up timlines, bringing them closer to her current one. So really, Astrid is talking to Ediyas from a time that is WAYYY after his. One of the reasons she could've survived alternia is because she wears a fake sign, which is obvious. Mainly it is assignable that she never left her hive, and when she did she posed as an olive blood.

Her lusus was a 14 foot tall praying mantas, which she called 'prayingmom'. Need anything else?

Alright! Cool!