I seem to remember reading once that what is typed by a stenographer is also only meaningful to them. And therefore must be transcribed into English later by the same stenographer.

Can anyone here confirm that?

That used to be true but it's much more automatic now that the process involves a computer translating into English in real-time (it's no longer a stenographer translating from their notes by hand).

What stenographers capture is phonetic. These days a computer program translates that back into written language in real time. It uses knowledge of the language to pull this off. So it's a bit like autocorrect on you phone.