It seems like your raw files have a mix of ambient exposures with shutter speed variation and then a couple of flash exposures. In photomatix, you would need to manually enter the exposure value of the flash images if you are going to use those images.
Also, the exterior areas of your image are purple-bluish because you have two different color temperature light sources in your image - the interior is lit by a lower color temperature (warmer, say around 3000 °K) source (the ceiling lights) and the exterior scene is lit by daylight, which is cooler in color temp than the interior (say, 5100 °K or so) and shade, which is even cooler (say ~6500 °K). If you white balance for the interior, you will shift the exterior lighting more toward blue, which will result in the appearance you see in your image. You will need to correct the cast in the exterior portions of the scene with a mask or a blend if. This is a common issue when shooting interior-exterior scenes. You can try a different route which involves illuminating the interior exclusively with flash, possibly gelled to match the exterior color temp. You can use a single flash and take multiple images with flash illuminating different parts of the scene, then composite those images into a single result. You can use a high shutter speed (at least the sync speed of the camera) to cut the ambient light from each image, then take a single, well exposed ambient shot without flash the blend into the composite. This way you avoid the multiple color temperature problem and have more control over the lighting in your scene. You would also need to take a high shutter speed shot without flash to capture the windows and other portals to the exterior correctly, and then blend these into the composite as well. It goes without saying that all of this requires a tripod.
You can also merge the three ambient images in photomatix two times - once with a tungsten WB and once again with a daylight WB and the blend the results using a mask. The overall merge in Photomatix will be identical and, if you use the same tone mapping settings, you will get the same result for the two images, just with different color casts.
The interval that you used between the ends of your exposures probably need to be expanded slightly. There is a lot of banding and clipping artifact in your Affinity Photo merge indicative of clipping in the source images.