Could it also be translated "they were preparing"?
they were preparing for smth - вони готувалися до [...]
they were preparing smth - вони готували [...]
what is wrong here with "has cooked"?
First, they requires have, second, have cooked would be приготували (perfective aspect), not готували (imperfective aspect)
oh, sorry, my fault, thanks
I put they cooked and it was accepted. It sounds a little weird in English, but it's used.