I suspect this one will be challenging.
At least here in the American market, the original automation systems were very expensive. Added to that, some of the better companies enhanced their hold on you (the customer) by forcing the sale of specific audio cards, which were serial locked to the software. The software wouldn't work without cards they supplied, and the cards wouldn't work without the specific software.
Then, there's the matter of the audio files. Some companies used encoding that wasn't compatible with wav or mp3 files, which was another factor that made it hard to move to a different system.
In '92, we bought a DOS-based system that eventually became one of Scott's products. I think I paid something like $15,000 for the main system, the switcher and a production unit. At the time, that was considered a bargain price.
The last DOS-based system I got anywhere near was from Pristine. It also had that proprietary lock on the audio card, wouldn't overlap anything and inserted a nice click between every file it switched to. We pulled the last one out a couple of years ago.
Good luck with this. I'd like to hear what you settled on, if you do find something. Was the kind of output you're looking for even available back then?