**Need "As Written", as there are many "opinions" out there.
Ethereal confusion: A Night Hag, while in the ethereal plane, sees and touches someone in the material plane with the "Nightmare" (Magical) ability. Does that mean the hag can cast spells like counterspell in the same way?
The hag can both see and interact with things in the material plane while in the ethereal plane. The "nightmare" ability is magical.
Spells like "Counterspell" are vision-based.
And yes I saw the fake JeremyECrawford's tweet about planes being infinite distance away, but that account has been removed and all the tweets from that account are considered tainted, biased, and in my opinion, null and void. It was not actually Jeremy Crawford who posted it.