@Ondřej-Šutera First of all - thanks a lot for getting back on the subject so quickly.
For Europe – this is the most reliable source I know with highly precise and responsible information:
https://www.dhv.de/db3/gelaende/
If you need assistance in terms of communication with the DHV (which is the umbrella organisation for paragliding in Germany), let me know - they also would be very interested to publish only legal information/ spots.
For the rest of the world - I don´t know – but if not here in this community, where else to find the good answers. And I´ve been browsing through several communications here where people do seem to have a good knowledge about their countries and local conditions.
But even that I am willing to discover if you're seriously intend to bring your database to the next level.
Thanks a lot!
Alex