This is definitely a bug in the Adventuron to DAAD exporter / mapper. I've chatted with Uto about this particular issue. It cannot be caused by DAAD ready. This can only be caused by code, so when Adventuron exports the code, this is where the magic happens.
What I can confirm: this is not bug in DAAD and saving a DAAD game on the Spectrum Next works fine. Same counts for loading. See https://8bitgames.itch.io/rabenstein as a reference, where it perfectly does the job. I just tested it on real Next hardware. Well, I did before but I wanted to be 100% sure.
Note: ERROR4 in the Spectrum interpreter means "OUT OF MEMORY". This can only occur if the commands that the interpreter tries to process are too long for the machine.