(Sorry for format issues, I'm on mobile)
I'm glad to see there's a thread here to talk about these now, thank you
@Hey Johnny Bravo for telling me about it!
I went down a crazy number station rabbit hole in 2015 and monitored sites like Priyom and
numbersoddities.nl for recordings and schedules. This one has a bigger catalog for recordings people have caught over the years, mostly odd occurrences like pirate interference and tech failures, including a few that confirm that some of these are still being operated on windows xp. There's also recordings for stations Priyom doesn't have on their site.
I'll go through my hard drives and see how many recordings I still have. These were fun to follow in a creepy-cool type of fascination.
Another Web SDR I have used before was KiwiSDR, which Priyom had been linking to for upcoming scheduled number station broadcasts, but it seems like it's been since reformed into something less casual-friendly than the one linked here in the OP. This was great because if you knew where the transmitter was based, you could choose a receiver location on KiwiSDR to get a clearer signal.
Oh, here's a fun thing: like many stations during the Cold War, E03 "Lincolnshire Poacher" had a sister station.
E03a "Cherry Ripe" followed the same format and was traced to the southern Pacific Ocean and had been shut down a year after Poacher.
All of my knowledge is on mostly defunct stations but I know some are still up and running.