You have learned how to properly read spell scrolls, even if they spells on them don't belong to any of your classes. Whenever you use a spell scroll of a spell that isn't on your class' spell list, as per the Homebrew rule for scrolls, you don't have to roll an Arcana Check in order to cast it, unless it is of a spell slot higher than you can cast or would've been able to cast, if you were a full-caster.
Additionally, you have advantage on Arcana Checks to determine the spells on scrolls.