Frankly, I am not sure Rune Magic is something that needs to be sponsored. It doesn't seem much different from Thaumaturgy, with refinements taken for more focus and enchanted item slots. Ms. Gard does put up wards and the like around Marcone's home does like anyone with Thaumaturgy could do. Did everyone forget that? Her consumable runes are just potions, and so it isn't hard for her to have them be quite powerful.
Seems to me she has something like Thaumaturgy, with Refinement x 2 for more item slots, possibly more refinement than that for a focus item to make her better at creating runes so she doesn't have to invoke as many aspects to buff them up. With Lore 5 she can make 12 one-time effects with 10 power, and that's pretty darn potent. One could argue her lore might be 6 or so though.
Anyhow, there's no particular need for her to have sponsored magic, I don't think, though I suppose being able to grab some debt to invoke an aspect wouldn't hurt.