So, in building this house mod I've obviously inserted a bunch of furniture, but not all of it is interactive, as in it can't be used. I threw in a couple of thrones, and they worked right out of the box when I tested the mod, but I have a number of different chairs that I can't sit in because there's no "activate" option showing when I go to them. Same goes for my Talos shrine, which looks nice, but has no affect. Chests, cupboards and the likes works just fine out of the box too.

Is there something specific that I have to do to make all these items interactive? Seems odd since the thrones worked automatically.

Sounds like you have placed "static" (not interactive) items in the CK. In the Object List you need to use the World Objects/Furniture items----they will have a chair/etc. icon and not the blue icon. Anything in the "Static" section you can't interact with.
The thrones you found only come in the non- static version, I believe.

Ah, that makes sense. So they need to show the blue person marker in the CK. Would the shrines etc. be in that category too? (I'm not at my home PC right now)

Yes, they are. There are a few static thrones in dungeons but they are mostly "destroyed", etc. There are statics you can interact with, but they are listed as "moveable statics" and are the things you pick up or can "kick/move/open" etc.

Awesome, thanks.