So different degrees of cousins are like musical notation; gradually developed over time with little regard to logic or utility. The chart noticeably endorses the popular, though incorrect, notion of a 'Great Uncle', current even before Bulgaria was a lad.
My nephew became a father last year: if I'm not a great uncle, what am I?
"Cousin once removed" looks logical to me - although there is no distinction between the two individuals, the relationship between the two people is cousins once removed. (All relationships more remote than first cousin can be referred to as cousins). It is true though that most intergenerational relationships have different names for the two, e,g uncle/nephew.
There are oddities in the nomenclature - for example there are usually both gender-specific and gender-neutral words for such relationships, e.g brother/sister/sibling, but there is no gender-neutral word to describe your uncles and aunts, or your nieces and nephews, and conversely no word that identifies the gender of a cousin.
Not bad, decent mixture of things and at least one bit of railway info I knew nothing about.
Mrs tbf, not as well-informed about domestic railways as me, thought it was fascinating and quite well presented & that is the target audience, I suspect.
And if you call me brother now,forgive me if I enquire, just according to whose plan?-Leonard Cohen Story Of Isaac We don't want to save the world, we want to kill the human race-The Meteors Teenagers From Outer Space