Rejestr Szkół i Placówek Oświatowych
Rejestr Szkół i Placówek Oświatowych – official database of schools and educational institutions in Poland, maintained by the Polish government. It appears to be usable as a potential data source from side of copyright and copyright-like restrictions.
Copyright IANAL analysis
It has no explicit license, but it has also no info about any restrictions.
Maybe it is exempt from copyright as an official document? See https://commons.wikimedia.org/wiki/Commons:Copyright_rules_by_territory/Poland#Not_protected But database rights...
See also https://dane.gov.pl/knowledgebase/useful-materials/faq where extracts from this database are published, apparently on an open license that may be sufficient for OSM. "The recipient should inform about the date, time of completion and obtaining information from the obliged entity" is specified as the requirement, maybe it can be fulfilled by proper changeset comment/tags.
Note that Polish text is "Odbiorca powinien poinformować o źródle, czasie wytworzenia i pozyskania informacji od podmiotu zobowiązanego" – and mentions also that "Recipient should be informed about source, production time and download time from the obliged entity" (translation was not made by a lawyer, author of this page is not a lawyer but "źródle" clearly disappeared in translation).
In August 2020 website operator replied whatever data may be used. Reply was not 100% clear, but it seems that we can use it.