SPOILER question/observation about a small detail

[Oliver]

Spoiler

Hey guys so I just visited Arthur’s grave, does anyone know why his grave has a Celtic cross? Cause I remember Sean used to call him English, and from what I gathered his parents where American? 

Morgan is a Welsh/Irish surname originally so maybe it’s just because of his ancestry but I feel like there is a more relevant or obvious reason I’m missing? 

Also interesting is that the most Irish of all Irish characters ever, Sean, only has a regular cross at his grave. 

This leads me to believe that Arthur’s cross maybe doesn’t represent anything at all and it’s just the design rockstar decided to go with, but isn’t it a very unique way of building a cross and a huge coincidence if it isn’t meant to be a Celtic cross?

 

[D3x]

I think they may have messed up. I questioned this myself...

Spoiler

I think the cross on Arthur's stone should be on Sean's and the one on Sean's should be on Arthur's. Maybe they messed up, which is what I am thinking... Or there is a reason for this that we are both missing.