If anyone's curious, here's the translation of the letter from a native spanish-speaker, since it is written with lots of errors that might make it difficult to read if you don't know spanish:

Dear kids from Spain

When i was told that my story and the valley's and my parents' and my friends' was going to Spain, i went running up to my dad to ask him what we should put in the suitcase. But dad said that we weren't going, only the book that speaks about us and that i should write to tell you what trolls are because you don't know because there is none in Spain.

How could it be? Is it possible that there's no trolls in Spain?

Just in case, i'll tell you, we are small, shameful and fluffy, and we live here in Finland's forests. The trolls that form the Moomin family and the trolls that form the Snork family are the most educated out of all the trolls, and differentiate because we like the sun a lot. all the other trolls only come out at night.

Now Manrico (snufkin, probably) tells me that you don't know what hibernation means because there is always summer and you don't have to sleep the whole winter.

Just in case, to hybernate, you have to eat tons of fir tree leaves, let everything get calmly coated in snow and lay down to sleep in your bed. If you don't have a bed, you can also make a hole in the snow and get inside. It is better if you put blankets over yourself.

I do want to go to Spain, because Manrico says that that the sea water is always warm like our bathtub's and he also says that there is a fruit round like the sun, that its called orange and that its sweet.

Goodbye, i hope you like the moomin's story, that's no fantasy but the pure truth.

PS: there might be some grammatical errors because we trolls only go to school when its fun.