Esperanto medium school is not possible ?

I was totally disappointed with this statement from a senior Esperantist.

Is Esperanto for intercommunication of different tribes or merely for international levels ?

Yes, many Esperantists still trap in many parts of their understanding of the language.

For example, South Africa, should not she adopt Esperanto as the nacia lingvo instead endorsing more than 10 languages as official languages. The cost of translation is enormous.

How sure you will be that the minority tribes, the number of the people will not be increased ？

I wish the senior Esperantists could make sure of the use of Esperanto is clearly spelt out in their mind and daily instead of giving false information about the use of Esperanto.

Can't a nation adopt Esperanto as a nation language to maintain equality of linguistic rights and to protect the local languages from dying ?

You find out who this senior Esperantist is and perhaps, you might want to give the esperantist a lecture the true meaning of Esperanto

Unless a school is specifically intended to be for international students with many different native languages, I don't generally support the use of an international language in a school.