Well, good luck I try as hard as possible to avoid such lighting fixtures that solely rely on indirect lighting because they can get extremely noisy. I try to use area lights in a direct fashion, and as big as possible, leaving only emission geometry for the camera only.
How would I approach such a scene? First of all I’d get hold of a real light so you know you’re analyzing the real deal and not some rendering where you don’t know what tricks are being utilized. But my general setup might be something like this:
Even 1000 samples with adaptive sampling enabled leave a noisy mess to denoise, and it shows. The 2 sample preview shows why this is the case. The top emission node is not using any trickery, while the bottom one mixes Quadratic (realistic) and linear falloff. In this case, the results are kinda close. The brightness of the walls will have a major impact, here I’m at 0.8 with some specular but without utilizing any reflection caustics for light transport. A dark wooden floor is not going to help the light bounce around. I’ve also upped the diffuse bounces. You can get some control by rotating the lights and controlling its falloff angle. The lamp itself is just a curve object, so ignore the missing ends.
Lighting a scene with these sorts of indirect only lights is just asking for having to do lots and lots of samples to clean it up. If this is a scene from other software, I’d ask or download to figure out how it was approached even if the software is different.