What is the genre or tag in Japanese terms for CGDCT? (Cute Girls Doing Cute Things for those that are not aware)
I'm not aware of the Japanese having a word for this.
It's overlapping a fair bit with
healing or in Japanese Iyashikei
癒し系 ( いやしけい ).
But it is not the same thing.
Not sure about today, but years ago when
cute girls doing cute things was first used (around 2008, as far as I remember), it wasn't really to categorize anime. It was to make fun of them. For example "does this anime have a story or is it just cute girls doing cute things?".
In that sense the origin was a lot closer to healing than what the literal meaning of the phrase describes.