It's pretty hard to put some celestial bodies into certain tags, so here's quite a lot of suggestions for it (examples in brackets)
Ringed - Celestial body that has a ring system (e.g. Merak )
Unrealistic - Celestial body that would most likely be unable to exist if it were real (e.g. Spinar )
With Structure(s) - Celestial body that has at least one structure on it (e.g. Merak again)
Fictional - Fictional celestial body (self explanatory) (e.g. a lot of stuff)
Replica - Replica of an existing IRL or fictional (like from another game or movie) celestial body (also self explanatory) (e.g. HyperPatch's Earth )
Black Hole - Celestial body with large mass that sucks things into it (e.g. Supermassive Black Hole by SergerjGrauberger )
Clouds - Celestial body that has clouds (e.g. Droo)
Ice - Celestial body that contains large amount of ice (e.g. Boreas, Mraz)
Volcanic - Celestial body which has past or present geothermal and/or cryovolcanic activity (e.g. Sedrema , Nyr )
Liquid - Celestial body that has liquid on it (e.g. Nekavir , Merak...)
Full Liquid - Celestial body whose surface is mostly or completely liquid (e.g. Tetra )
Habitable - Celestial body which host some form of life, e.g. vegetation or animals (e.g. Merak, Earth...)
Brown Dwarf - Celestial body that does not have enough mass to be a star, but too much mass to be a planet (e.g. Efidiris )
Pulsar - Small and compressed celestial body which emits light beams (e.g. Purasaro)
Chtonian - A rocky body which is the core of a former gas giant whose atmosphere was stripped off of it (e.g. Citet )
Venusian - Rocky celestial body with a dense atmosphere and extremely hot surface (e.g. Venus of course, Vazur)
updated with some new ones