Wayne Chen (USA) provided a link with a video made by Lisa Berthin (Canada) from StampCat, broadcasting information about the 2021 Slania joint stamps including an interview from him. See https://youtu.be/Dkpx6C4YcKw. Nice to have the whole story and of course the full story of Czeslaw Slania covered within about 15 min on Youtube. Congratulations Lisa!