What string does it report?
In any case you should open a bug report at Issues · sipeed/platform-gd32v · GitHub with this information so that the tool-openocd-gd32v can be updated with a new configuration file for that debugger, plus the needed Python logic in the platform to recongize that adapter, as it seems to be different to https://docs.platformio.org/en/latest/plus/debug-tools/sipeed-rv-debugger.html