I don’t have the original letter of the sender containing the question(s), but we can perhaps discern what was going on.
Here is the main part of the PCED response:
You raise the question as to whether school children are permitted by right to be exposed to the celebration of the Eucharist in the extraordinary form provided all necessary catechesis is offered. the answer is obviously positive.
Of course, they are permitted to be exposed to the celebration of the Mass according to the extraordinary form. No doubt, a number of them already assist at this Mass with their parents on Sunday.
We trust the the priests of the Institute of Christ the King and those who collaborate with them will help engage the children’s participation in some way with songs or chants. we would also suggest that the readings for Masses be read in the vernacular as this is in full accord with the Motu Proprio Summorum Pontificum and could further help to maintain their attention.
I am guessing that the question we put to the PCED because someone suggested to the writer that TLMs are too hard for children, that Latin isn’t appropriate for them.
A couple things. First, we don’t know what age "school children" are. They might be 6 or 16, with rudimentary English or, perhaps home-schooled with Latin. Common sense must be used.
Also, from the onset after the text of the Motu Proprio was released I spoke of my option that the vernacular could be used during TLMs. That doesn’t mean I think it should: I am saying that Summorum Pontificum permitted it (as did the PCED’s guidelines many years ago). I am not sure about the best way to handle this, however. Perhaps the priest could do as he would during a low Mass on a Sunday, leave the altar and read the readings a second time. Perhaps he would not read in Latin, but rather read them in English. Perhaps someone else would read them in English while Father was reading them normally in Latin. I don’t know.
However, what the PCED wrote was a suggestion. It can be taken or not.
Also, songs and chants could be used to "engage the children’s participation". Well… okay. But I suppose that means having Missa cantata. Otherwise are we now into the thorny problem of the role of "hymns" and "songs" versus the actual liturgical texts of the Mass? I don’t know.
Another thing, and interesting, is that children have the right to be exposed to the TLM. They have a right. If they have a right, then pastors of souls have a duty to respond. And since there are children pretty much everyone, as memory serves, then pastors of souls pretty much everywhere have the duty to see that the rights of those children are being met.
Furthermore, since children themselves don’t know their rights or know clearly what is good for them, and they might even from time to time resist what is good for them, pastors of souls should nevertheless persevere in building up the TLM in parishes.
By extension, adults also have these rights. Pastors of souls should also see to the needs of their spiritual children even if no request has been made.