Nice shot! The main summit of Kangtega (6783m) is not visble on that picture, what we can see is "only" P6685m located 0.8km further west-northwest. here and here two other shorts from a different angle with the main summit.
Yes, you are correct. Here is another shot I took from Nangkartshang:
Interestingly, the mountain is not named for the highest summit, but is named for Point 6685m. Kangtega means "the snow saddle" in the Nepali language and is named for the slightly lower peak pictured here which is said to resemble a Tibetan saddle when viewed from Tengboche.
I will add the info to the photo.