Sounds like what we Euro cavemen call PAL-60. Which is usually a signal with 60 Hz, NTSC 480 lines resolution and PAL colour coding. This was an option supported by a lot of PAL GameCube games (some even ran only in PAL-60 like Metroid Prime 2), which might helped the developers to save costs when converting from NTSC to PAL, and we PAL gamers liked the option since it made shitty conversions obsolete. This mode was supported by a lot of PAL TVs starting in the 90s.
The PAL PlayStation 2 has a similar 60Hz mode supported by some PAL games as well, but this time it is true NTSC with the respective colour coding. Most PAL TVs back in the day needed to be fed with RGB signals to bypass the NTSC color coding when playing these PS2 games in 60Hz.
So I guess the CD32 hasn't RGB from the start?