Where are you getting that from? I know counting objects in Japanese is kind of weird, but I ran what you said by a friend who has a master's degree in Japanese and she says "First time i hear "ra" means 2nd and "ga" 3rd lol". BUT REPEATING THIS, I know counting in Japanese can be kind of weird especially when it comes to foreign words.
Also for reference I've dug up a
Japanese fandom guide to black magic throughout the entire series if you ever want to skim for what spells are called in Japanese for your own reference.