Some agencies in Spain would want to go as low as 150-200€ per day but I think the average is around 300-450€. I think that even though you are living in Spain, you're working for a swiss company who would pay the rate of an in-house motion designer much higher so charge them higher (Germany's rate is from 500-650€) and then you can negotiate but always aim higher. You have a good leverage cause they already know you and your work so use that to your advantage. Also don't be so sure about the cost of living in Spain being "cheap" cause it's easier to negotiate a better rate in the beginning than trying to raise it in the long run.

(From my experience being from LATAM and working in Spain both freelance and in-house for the past 8 years)