Have you checked your Windows language settings? Make sure it’s set to English (United States) and you have installed all the components in that language, like Speech recognition, Text to Speech, etc.
Do you happen to know which ICAO Airline flight was that? I do find some inconsistencies with Live traffic callsign but this is due to outdated ICAO database that they use.
For example, since I fly around Indonesian archipelago often, we have an airline with ICAO Code CTV with a callsign “Supergreen”. The problem is, there was also a pilot school in Spain with the same ICAO code of CTV that has a callsign “Are Aviacion”. Apparently the sim uses this older CTV callsign instead of the current CTV callsign.
Maybe it’s the same in your case, there might be an issue with the reference database where that ICAO flight code has this “Waypoint” as the callsign.