Colemak is designed for English, but it allows for occasional typing in other languages.

I haven't done any serious research for the Spanish language, but there are a few issues:
* The 8 most common letters (E, A, O, S, N, R, I, L) should be on the home position.
* The 9th and 10th most common letters (D, T) should be on the home row.
* One issue is that E/U digraph is very common in Spanish.
* Since the accent character is on the pinky, you shouldn't put vowels on the pinky.
So it won't be optimal for Spanish, but still way better than QWERTY.

There's statistical information for Spanish here, http://www.characterfrequency.com/part1.html . I can't say if the statistics there are correct or not, you also need to sum the lowercase and the uppercase.
I don't have time to work at the moment on Colemak, but I will release later this year more tools and information about the development of Colemak so it can be adapted for other languages.

The Spanish (Spain) keyboard layout allows typing in Spanish, Catalan, Basque, Galician, French, Italian and English. You need to consider how much of a sacrifice you want to make for each language.

Since everyone has different needs it's impossible to make everyone happy.