That divergent geopolitical opinion on the concept of "Ariya" and/or Aryans sounds like the one on the BhagavadGita. Someone considers it the "song divine" of the Kshatriya, while others already a late Bhakti book, even involving reincarnation in some point, an idea rejected by Evola.
Coomaraswamy is not the only one; many Indian scholars obtain their qualifications elsewhere – in the case of Hinduism students their prime choice of destination is usually Germany. Nonetheless I still read his works, as I do many other Indian writers. Many European writers on Hinduism have a natural prejudice towards Catholicism (O’Flaherty and her apostles) which tends to distort both her Sanskrit and its subsequent interpretations. Evola, however, was obviously immune to the Catholic meme.
Regarding the ‘Aryan’ content of Hindu’s in general there are two distinct types – those who think they are the Aryans, and those who wish to remove all trace of foreigners from their soil. Not surprisingly this is usually tied to their own geographic locations, as I am sure you are already aware.