Hi Jakub, it doesn't look like sloppy modeling, it looks more like just a difficult thing to fillet, in this juncture area here:



That piece coming down and ending at a point is at about a 90 degree angle to the other surfaces and filleting is going to have problems making junctures in a tight space like that. I'm not really quite sure what the proper result across that would be. I'll see if I can come up with any tips, it may be that filleting just isn't going to be feasible there and you might need to use other techniques like trimming away some space and putting in a blend surface instead. But that also might be difficult with the sharp 90 degree piece in a small area too.

- Michael