Had to look up COTA to find out it's Circuit Of The America's, although I should have known that, as I follow F1. More used to it being called Austin grand prix.
Not sure what the problem is with having Indycar there - they don't have to use the full circuit, as used by F1. Looks like there are 3 different configurations. They could always use the simpler East layout, if full layout too technical.
Not a racing series you tend to see on tv in UK, so know little about it.