So if you have sponsored magic, you can have thaumaturgical effects as rote spells? How does that interact with declarations?
Any declarations, intentional use of consequences, invoked aspects, or use of foci need to be built into the rote up front. The rote spell doesn't (can't) change when cast. You can build those into a rote but, if you can't use one for some reason, you can't cast the spell as a rote.
Frankly I wouldn't waste a rote on most thaumaturgy spells even when cast-able as evocation. One potential exception is a ward. (Perhaps this is how a certain wizard put one up so quickly!) For the most part I want rotes to be those things I need
right now - defense spells, veils, a utility boost, and perhaps one overcharged attack.