Can a non mortal magic spellcaster (for example, a changeling with Seele Magic or even a Sidhe) have some Rote Spells?
AFAIS he/she can just as it can use Thaumaturgy according to it's sponsor agenda. But I didn't find any example on the books.
Your World page 287: Sponsored magic emulates evocation and thaumaturgy.
Your World page 288: "Sponsored magic spells are put together exactly like evocation and thaumaturgy."
Also see several of the examples of sponsored power sources beginning on page 290, which make it very clear that anyone who has access to a sponsored power source can have access to evocation.
There's nothing indicating that someone with sponsored evocation power has access to only some but not all of the evocation rules.
And the lack of examples of non-human Rote users shouldn't suggest that they can't use it.