I don’t have Real Time Delays in front of me but I assume it uses Glulx timers.
I’ve run into this same error message with Glulx notifications. There’s a workaround here:
https://intfiction.org/t/if-archive-hugo-downloads/59/1
For some reason I thought there were plans to change Glulx Entry Points to handle this differently, though I don’t see it among the planned changes here:
github.com/i7/extensions/issues/23
Or maybe I’m not recognizing it–I’m not actually sure what all those items mean.