Not sure of your definition of good quality Transformers material, but there are six chapters of a Transformers/Girl Genius crossover on AO3 called Invasion of the Giant Clanks from Another World:
https://archiveofourown.org/works/211994...s/50464568
Summary: Millions of years ago, a vessel sailed across the stars and, due to the fighting aboard it, crashed upon a humble planet. Time and volcanic activity covered it up. Many years later, a dead volcano is merely the plaything of a Spark in Europa. An ordinary demonstration awakens the volcano, and more besides!
https://archiveofourown.org/works/211994...s/50464568
Summary: Millions of years ago, a vessel sailed across the stars and, due to the fighting aboard it, crashed upon a humble planet. Time and volcanic activity covered it up. Many years later, a dead volcano is merely the plaything of a Spark in Europa. An ordinary demonstration awakens the volcano, and more besides!
“I really hope I’m behind this convoluted mess; at least that way I’ll be able to get revenge by doing this to myself. I won’t even have to feel bad because it’ll be all my fault.” - Harry Potter, The Master of Death by Ryuugi.