That quote from Schnee seems odd to me. I mean, what do you get if you try to decompile the binary? That output should be more useful than "a database of every phoneme it had ever uttered".
And, as someone else pointed out in this thread, there exists an ISO and an activation code at archive.org, and it should be possible to get this running in Wine or in a VM. Someone clever could probably patch the binary to make it run on modern Windows. The distraught rabbis should community-source a developer.
All of that said, even if the source code were to be found, it seems likely that further development of the core functionality might be dead. This was a man's life's work in an esoteric domain; it might not exactly be accessible code.
I’m late to this thread but I actually cracked Trope Trainer open so I can help with the speculation. The interface to from Trope Trainer to the DECtalk DLL is just strings of ascii phoneme names and pitch and duration information. The code that generates those strings has simple parts and complicated parts. There’s an encoding of the Hebrew scripture, an XML file that describes the musical notes for different “tropes” (in several traditions), an INI file mapping Hebrew letters to DECtalk phonemes (in several dialects). Then there’s a fair bit of code that actually ties those together. The old version on archive.org is written in Delphi, newer versions written in Xojo (REALbasic). That compiled code has very gnarly hand-written logic for Hebrew pronunciation rules, and all the logic for choosing which trope to sing for which biblical verse. It’s daunting in there, but if more people than just me were interested in reverse-engineering it, I’m sure we could get it done.
I have several physical copies of the last edition of Trope Trainer, with serial numbers. They don’t work because they try to phone home for activation. I think they have all of the actual code they need to run, if would could bypass the initial steps. Realbasic binaries are harder to debug than Delphi, and I haven’t had time to really dig into it.
And, as someone else pointed out in this thread, there exists an ISO and an activation code at archive.org, and it should be possible to get this running in Wine or in a VM. Someone clever could probably patch the binary to make it run on modern Windows. The distraught rabbis should community-source a developer.
All of that said, even if the source code were to be found, it seems likely that further development of the core functionality might be dead. This was a man's life's work in an esoteric domain; it might not exactly be accessible code.