On my machine, Max 7.3.2 on MacOS 10.2.3, the bgcolor attribute of the comment object works fine but it's the textcolor attribute that can't be set by a message, although textcolor can be set with the color wheel in the attrui, or via the Fonts dialog box and the attrui will then reflect that change. I note that 'textcolor' is not listed in the reference manual as an attribute of the comment object, so I suspect that this anomaly of not responding to a textcolor message is due to a bug in the comment object. You can report bugs to support.

Hmm. I just experimented a bit further and found that the 'textcolor' message doesn't work if just RGB information is provided. It appears to work only with RGBA.