Myne from Bookworm
Later on in that series, after having previously done so with another spell, she basically 'create' a new spell.
The invocation? "Copy Then Paste"
Then after the initial joy pass, she realized she fucked up the "Copy AND Paste" phrase.
But since it's already registered she can't change it anymore.
Even later on...
Ferdinand "See this? The font size of your copy and this are different, it might be fine for texts but for magic circles this won't work"
Myne "Umm ummm, maybe I can try to see if I can resize it..."
Ferdinand "What absurd-" Myne "I did it!" "-thing....never mind, just keep going then"