Should the old building roof be insulated YES or NO

Hello everyone

We are considering buying an old building and the roof there is not insulated. Only a kind of foil under the roof tiles can be seen.

So far everything looks dry.

Is there a general insulation requirement for the roof or does it only apply when the house changes owner?
I also read about a 2-year deadline.

I am totally confused because I would like to know what might be coming our way, even before an expert comes along.

P.S. If you want, I can also take some photos. That is probably more informative than anything else. :)

Here are two photos on the topic. :)