You’re right on complex objects, of course.
For a lot of things though, just the difference between preview and production builds is radically different. This will often resolve a lot of issues with light leaking.
I’ll get to some feedback in a moment, but to touch on the dynamic lighting first. There is going to be some edge leaking here regardless. The shadow bias and filter options help reduce it, but it won’t be perfect.
Ray Trace Distance Field Soft Shadows is a good alternative though for getting better dynamic shadows for your static meshes as well.
Back to your mesh.
There are two things to start out with that I notice that may help.
I can see you have two lights in your mesh. You have a spot light near the top and a point light at the bottom. Is there a reason to need both?
You seem to have a lot of small geometry in your LM. If the chain is part of that small geo, which it appears it may be, it may be better to up the size in your UV for it. As a test, try using the generate LM in the mesh editor and let the engine repack this LM for you. Depending on the repack and if it re-sizes pieces you could see a better result.
As an example of a light fixture I’ve attached one that Eric and I used for our side project. I’ve used this as a test to see if I could get light bleed on mine, even in preview it’s not seeing the bleed. This is probably related to how my UVs are laid out.
What you can do to get more space would be the reduce the size of the fixture hull by almost half and resize the other objects to fill the space and not be as small. This should help in getting you better LM resolution for the smaller objects, since you don’t need the LM quality for the hull to necessarily go any higher.
I hope this makes sense. Let me know.
Can you also post images of your details panel for the Spot and the point light you’re using.