author, ama

I know page design ≠ implementation of design but the poor font colour pairing doesn't lend much credibility.

I don't get it - what's wrong with the colour pairing?

The greyscale text is way too light. Very hard on the eyes.

Hmm, it's possibly more the font, your system's font rendering, and/or your display than the colour.

It's an easy pass for WCAG AA with 5:1 contrast ratio, but I think it's marginal for WCAG AAA as it's about 20px in size, but not bold.

If you're finding that hard on the eyes it might pay to check your display's brightness with a colorimeter. Most displays are far too bright out of the box.