Should precast concrete filigree ceilings in the basement be left unplastered?

and only the joints between the different individual parts

Where do you see visible joints there?

To be honest, you won't get even the slightest hint of a loft look with either filled/painted ceilings or completely untreated ones,

I think the "loft look" is not taken more seriously in this sense than the "concrete look" (which is also only very symbolically called that in fashion furniture).

Where do you see visible seams there?

The precast slab consists of some prefabricated parts that are "laid" on the walls. After that, the concrete slab was poured on top.

Between the individual parts (there are not that many, maybe 2 to 3 per room) are the seams I meant.

Next time I'll take a picture at the construction site and upload it afterwards for illustration.

Where do you see visible joints there?

Really? Ever been inside a shell construction?

The "rustic" charm of the loft also has the peculiarity that the ceiling is farther away from the viewer. A delicate ceiling viewed from one meter away simply looks really unpleasant.
I would at least fill the joints with concrete filler. You don't necessarily have to sand it in the first pass; it can already look good that way. You can still continue filling/sanding, and possibly painting later.

Between the individual parts (there aren't that many, maybe 2 to 3 per room) are the joints I meant.

Really now? Ever entered a shell construction?

Really now, did you just ask me that?
"Filigrandecken" (R) do not have fundamentally different sizes than purely in-situ concrete ceilings, and most ceiling panel boundaries are, seen from below, practically hidden by the walls. Only in very large rooms (like the Wohneßkoch suite, for example) – and thus in hardly any relevant number overall – would I even expect joints running within a room; hence my follow-up question.

Seriously, did you just really ask me that?

Yep. After your post #10, I could ask that again.
That can only be satire.

Of course, filigree slabs are limited in their width, if only for transportation reasons, and therefore are not "mostly" sufficient as a single piece to cover a room. That distinguishes them significantly from cast-in-place concrete ceilings.

This room is about 2.75 wide... @te We will leave it as is, is the HAR