I have a very simple question, I would like to indicate the center of these 2 holes, so that I can put a rating on them. Anyone have an idea to do this well? (without making a sketch "by hand")?
No, unfortunately, a rating must necessarily hang on to an entity.
When positioning the points in the "Drilling Assistance" function, simply create a construction line connecting the 2 points, then for the dimension you have to select the middle point of the line.
Otherwise, in the drawing, draw a construction line, then select this line and the 2 circles of the holes. There you will be offered a symmetry relationship between these 3 entities and your line will be perfectly centered.