Hello Alec,
Many thanks for looking into this.
I appreciate that you determined that VLC also does not display the diacritics correctly. However, I have determined that TuneIn does, and have written up a report, with pictures as evidence.
The only way that TuneIn would be able to render the diacritics correctly if the stream is incorrectly encoded is if somehow Bru Zane supplies one stream to TuneIn and a different one to Roon, don’t you think?