Houdini Engine (HDA) Instance Building lightmap different to .fbx model

Hello everyone.
The last week I made my first steps with Houdini Engine in UE4 and I am pretty happy about the workflow and the posibillities.
I was following most of the tutorials I found about Houdini → UE4 and also purchased the cool Mixtraining Course.
So the basic topics and technics in both programms I kinda understand.

But there is one problem, that makes me nuts since friday and I dont know, how to solve that.
I also talked to Varo and when he tries to reproduce my scene, it works. When I do the same steps, I get very strange results and I dont know, why.

I attache some pictures, to show what I try to do and where I am atm.
Thats a render test with Redshift:

Just a simpel hall with sunlight coming in from the outside and these lamps on the ceilling.
The pic below is with the texture that was provided with the model and no lights on the ceilling.

This next image is the model, rebuild in Houdini and generated an Houdini Digital Asset. Dimensions, models etc are still wrong, but I wanna focus on the light first and understand the workflow:

I was following a tip from Varo, to “Replace with Blueprint”. I was searching for that function, but still dont understand, what thats doing with the asset actually.

So now to my actuall problem:
In Houdini I instance one of the building parts with “copy to points” along a curve. So I can change the number of windows and the withd/hight of the room with Houdini Engine in UE4.
But Ill get very bad lightmap quality like seen in the image.

When I export a single room part as a fbx and import into UE4 and duplicate by hand, the quality of light is way better.
With the Houdini Digital Asset I have to increase the lightmap resolution alot to get some kinda good quality, with the .fbx model I get better light with less resolution.

Here is the HDA file, just in case:
[HDA][3]

Could someone explain me, what I am doing wrong and why there are so big differents when using HDA or imported .fbx parts?
Thanks alot.