Sunny had no clue how to create, decipher, or manipulate runic magic. His inherent ability to see the weave and inner structure of magical items, the one he had received after consuming the drop of ichor that fell from Weaver's eye, also gifted him with an innate understanding of the essence of spellweave.
While studying the Memories created by Spell, Sunny was not able to fully understand the intricate purpose of the vast patterns of ethereal strings… but he at least could intuitively feel a hint of it.
He had no such advantage when it came to other forms of sorcery. So, despite the fact that he had managed to perceive the enchantments encompassing the Red Colosseum, it was not like he could simply change them, or create new ones to counteract the old.