Besides all the so called legal banking business handled across borders and even worlds there are all manner of deals that no one in their right minds would ever call legal. Selling guns, bombs, and sex are all legal on some worlds, but none of these are legal on EVERY world if you get my drift.
But bad people need to keep records of their deals and sometimes even a transcript to indicate exactly what one or the other had said. At any decent tech level a transcript can cause you severe trouble. To make one a talk to text system is needed and the audio files of course can be examined for speech patterns, voice characteristics, probably even DNA by TL 15. Don't tell me that stuff gets wiped. It doesn't have to and then some punk has a shady deal to hold over your head. Note someone smart enough to make and secrete a copy of an audio file probably is smart enough to make several such copies and give them to various people for release upon their death.
Enter the Zaonians yet again! Their handwritten records already put the brakes on forgery and fraud in their cluster. It seemed only fair that they do something for the crooks now (for a fee of course). Now they stepped it up into a system of recording meetings and discourses of various types in great speed and and accuracy/ I refer to stenography!
If handwriting analysis was regarded (by those poor ignorant hi-tech folk) as mad science steno was a glimpse of Great Cthulhu. You mean people can write as fast as they can talk?! Impossible! Untrusting souls would have to find a stenographer they both trusted or more likely hire their own and thus make their own transcripts. All this had to be carried out on Zaonia of course for complete secrecy. On Zaonia any bugs built with local technology would be about the size of a beer cooler and the tech knights were keen on keeping offworld tech offworld.
In fact they even used psionics to sniff out hi-tech smugglers. Psionics isn't a form of technology! But I digress.
The people interested in having their meetings transcribed would be brought to a secluded conference chamber. The recorders could in fact be ordered from several agencies with complete anonymity and ignorance of both parties to insure their honesty and impartiality. The stenographers would take dictation during the meeting using shorthand then typed out the transcripts. No voice files to incriminate. Accurate recordings of vital matters and agreements were made. Best of all no hard forensic evidence to identify the parties of the agreement in a court of law (though they knew who they were of course).
The Zaonians still were security minded. When their banking guild set up an official agency to license and monitor stenographers they added additional procedures, such as the stenographers using a newly constructed system of phonemes for their note taking. Previously they used a more or less accessible phonemic writing system that could be discovered on library systems because it was commonly used in the past. The extra benefit of phonetic writing was the stenographers no longer had to know the language of the parties meeting. They could record it in their notes in their con-lang scrawl and type it up using a phonetic alphabet system common in the cluster. The original notes would only be of use to another agency scribe who knew the con-lang.
The Voynich Agency was in business!