lens looks absolutely OK to me if the sharpness is your concern. If you want to test lens for the sharpness in the field, you basically have two options…
a) testing it for lab like results (in the mid frame only) to see its full potential.
b) testing it similar to the way, you intend to use it.
While in the first case, you’ll might be able to comment on the lens sharpness in general, you’ll have to build very strict testing routine, excluding all possible variables (sturdy tripod, good light, good focus target with high contrast, good weather conditions (humidity, haze, heat etc.) different focus distances, several shots per aperture with slight shifting of focus plane, base ISO only, flare prevention and most importantly, sturdy tripod with remote triggering.
You went with second option, trying to figure out how the lens will work for you. I can’t thus comment on the particular lens and its resolution rendering capabilities, but looking at your gallery, I don’t see any major flaws, such as blooming, explicit CA etc., things that will reduce native resolution.
In order to find out if lens is capable of rendering full sensor resolution, you’ll need studio lab conditions and lot of experience. Maybe you can find somewhere MTF figures for your lens, which should give you an idea.
In a normal life, there are too many aspects (slightly missed focus by 0,5-1mm e.g.) that will affect resulting image resolution, which will come before you hit lens resolving limit.
In your case, you should also think about shutter shake being a serious threat for critical sharpness. This lens, used on monopod as you suggested is among most affected combinations for reveling this phenomenon.
In summary, I don’t find anything wrong with the lens from your images, slight blurriness in some of the images might have many other reasons before resolving limit, shutter shake (on A7R) can be one of the main reasons why you have inconsistent results.
Hope it helps,