I have built 5 different versions of COTA, not on Eifel Flat but Eifel, fighting against the absence of elevation control in TPE.
The results are quite good, even though in the first 2 versions some corners are just ridiculous, while in the last 3 versions the elevation of turn 1 is not good enough while there are elevations where there should be none.
It's not that we all could not build good courses, it's just that TPE has too many restrictions and not enough features
(e.g. why can we underlay a picture only in Eifel Flat and have to work with transparent foils in the other 3 themes when we want to build a replica of an existing course?).
Maybe you want to see my attempts?
You can find them here:
COTA Version 1 (bumpy)
https://www.gran-turismo.com/gb/gt6/user/#!/friend/Ema-Nymton/course/1541464/
Version 2 (a little bit less bumpy)
https://www.gran-turismo.com/gb/gt6/user/#!/friend/Ema-Nymton/course/1541717/
Version 3 (not too bumpy)
https://www.gran-turismo.com/gb/gt6/user/#!/friend/Ema-Nymton/course/1564060/
Version 4 (from a different stating point)
https://www.gran-turismo.com/gb/gt6/user/#!/friend/Ema-Nymton/course/1564543/
Version 5 (as flat as it gets without losing elevations)
https://www.gran-turismo.com/gb/gt6/user/#!/friend/Ema-Nymton/course/1564935/
