Hi Varti,
Thank you so much for your efforts! I can tell you that you are the only person known to receive a reply from the author on this topic for 10+ years

So great job.
The link to YAE is very useful information! Recreating the emulator looks like the way to go. I'm not setup for that currently, nor do I have the knowledge but I do hope to setup a development environment sometime in the future. I believe that I have all the SDK files, tool chains, etc. that I need along with some versions of Linux from that era.
It is surprising that zapple never made it into a feed someplace where it may have survived. The quest continues...