Ok, to keep it simple:

My Father identifies as black. My Grandmother, of whom I am fairly certain is my Grandmother due to extreme family resemblence, is light skinned with a supposed black father and a mother who is probably 1/8th african. My grandmother was married several times and this man she married when he was 51 and she was 30 and he died before my Father was born. From pictures, he is extremely dark.

My Mother has 3 Irish grandparents and 1 half irish half swiss grandparent.

I was able to make DNA connection with the half swiss grandparent out of 35 4th cousin matches.

My DNA results came back:
60% Irish
12% Europe West
9% Great Britain
10% Benin Togo

Trace:
3% Italy/Greece
1% Cameroon
<1% Caucasus
<1% African SE Bantu
<1% Nigeria
<1% Africa North

So this would seem to me to pretty much rule out this man being my Grandfather to me? I know the tests aren't "superbly" reliable but all of the DNA matches and the albeit limited family trees seem to not match up. I was actually able to get my family tree back a fair bit (presuming correct paternity) and I see almost no matches in surnames for 4th cousins (Great Great Great Grandparents) except for a probably sibling of my GGGP who shares benin/togo and the surname of my father's mother's mother mother.....

I'm not a geneticist and barely even an amateur genealogist, but am I look at this wrong?

List of Great great grandparents:
Edwards --- PATERNITY DOUBTED
Unknown Edwards spouse - DOUBT
Sinkler - DOUBT
Unknown Sinkler spouse - DOUBT
Drew - PRESUMED ACCURATE: 100% African Assumed
Jones - PRESUMED ACCURATE: 100% African Assumed
Hunter - PRESUMED ACCURATE: 50% Irish 50% British Assumed
Hicks - PRESUMED ACCURATE: 25% African 75% unknown presumed
Shanley - PRESUMED ACCURATE: 100% Irish presumed
Creighton - PRESUMED ACCURATE: 100% Irish presumed
O'Neilll - Nurse child so name inaccurate but PRESUMED 100% Irish
Unknown Irish spouse - PRESUMED 100% Irish
Trainor - PRESUMED ACCURATE: 100% Irish presumed
Unknown Irish spouse - PRESUMED ACCURATE: 100% Irish presumed
OHearn - PRESUMED ACCURATE: 100% Irish presumed
Bindschaedler - PRESUMED ACCURATE: 100% West Europe presumed

Me per DNA test:
14% African
2% Other
60% Irish
12% West Europe
9% British
3% Italy/Greece

Identified:
14% African
46.875% Irish
6.25% West Europe
3.125% British

MISSING:
13.125% Irish
5.75% West Europe
5.875% British
2% Other
3% Italy / Greece

Therefore, missing roughly:

TWO Irish Great Great Grandparents
1 West Europe Great Great Grandparent
1 British Great Great Grandparent
1 Greek/Italian/Turkish mixed Great Great Grandparent

Or something darn close to that? Which would seem to utterly preclude the one grandfather being the man I thought?