Hi Hilaire,
The instructions are written in small characters, which supposes that the child who tries the exercises is rather old; yet before a child is able to read complete sentences like this, he/she learns the numbers. So I wonder if your application would not benefit from voice synthesis.
Which yields me to an other question: Is there already voice synthesis in Pharo?
There KlattPlugin but it is prehistorical age and does not work for spanish, french.
I had one student working on bring a tagger.