Thank you to all who commented.

I put some good weight through the bar this morning and there was no apparent widening or sounds from the bar, which was comforting.

This will be very hard to explain but i'll give it a go. The way the base bar is build, there is actually an inset portion where the spacers bolt through. Therefore, it would appear that the part of the bar that is under tension is not actually on the top of the bar, where that "scratch" is. The part of the base bar that is under tension from the spacer bolts is deeper" into the carbon closer to the middle / core of the bar. This also give me comfort that the marks are more likely not structural, as it now seems unlikely for that particular area to have been affected by over-tightening. Happy to hear other opinions.

At this stage, I think they are scratched in the clear coat, however, I will keep an eye on them and, comparing to my photos, monitor for any change.

Cheers