I was touring another stronghold and the owner had placed an empire theme ceiling light that changed the mood of the room by casting a red glow on the floors and walls.

I cant find the name of this thing.

Are there other lights/lamps etc that do this?

It would be nice if there were "wallpaper" or "carpet" options to make each room feel different than the last.

There are a couple of lights that taint the room red. The intensity depends on the deco itself and the size of the room.

"Totally red" (like "room is bathed in red"): Imperial Ceiling Light

"Still quite red, especially in smaller rooms": Emergency Ceiling Light (Red)

"Noticeable red right under the light": Dynamic Underworld Ceiling Light (Red)

Some other decos that give off a nice "moody" light:

Zakuulan Standing Floor Lamp (the Star Fortress drop; not the "Zakuulan Floor Lamp" cartel market item)

Luminous Sconce: Yellow

Massassi Ceiling Light (yellow spot, but also very confined to the spot underneath it; similar to Dynamic Underworld Ceiling light)

Hanging Forge Lamps (beautiful light with some shadows)

Generally light decos are trial and error. Some only cast light when bloom is switched on in Graphics settings.

You can check my stronghold videos linked in my signature or other peoples stronghold videos on youtube to get a better idea (or, as you already did, visit more strongholds and try to identify the deco while checking https://tord.mmo-fashion.com/category/database/decorations/decorations-lights/)