> For many of us, some of these combinations are not very readable. That is why 4.5:1 is a minimal contrast ratio.

Having a thin stroke (the space font face) and small character size (18 px, which is a 12 pt equivalent) for your typeface typically means that you need to increase the contrast to compensate.

In other words, 7.5:1 is insufficient given the design choices. Even if it's "legal".

Guidelines are only a map, they are not the territory. The eye of the beholder is more important than the contrast ratio.