Yes wellness is a word, but spelled as well-ness in the dictionary
Greek word for wellness
wellness
Project wellness
Yes, the noun 'wellness' is an abstract noun, a word for a state of being, a word for a concept.
You're mistakenly assuming "wellness" is a proper word.
eating breakfast every day is a regular wellness
wellness
swastha
ni haosa
health.
health
== == Bienestar but a better term would be salud.