I have just checked through the earlier posts, and one piece of information you don't appear to have ever given is exactly what brand and model your video camera is. However, I am now assuming it is an AVCHD model... But can you please confirm.
One thing strikes in your latest post, and it is related to my question about your camera. If your camera is indeed an AVCHD model, then depending on exactly which camera it is, it will probably be filming in 1920 x 1080, UFF, Dolby 5.1 audio but with a maximum bitrate specific to that particular camera. Most middle of the road models appear to use VBR max 16,800 kbps; some have a max. of 18,000 kbps and a handful of the most recent higher end models are using the new max. of 24,000 kbps (which VS cannot seem to handle anyway as it was written before that new standard appeared...)
Now, in your 'create a file' properties, you show a VBR max. 16000 kbps (and what appears to be Dolby 2 channel stereo audio) plus, correctly, Upper Field First for AVCHD video. But what went onto your Blu-Ray disc was Lower Field First and a new, higher bitrate of 18000, plus LPCM audio. There are at least two problems with these differences.
First, we need to know what the exact properties of your original video files were *before* you created the new video file of your project. If the properties you gave above vary at all in terms of bitrate from the original, then the whole of your video would have been re-rendered, which -- being mpeg -- means one generation of loss of quality. And then you burned the new file to BD using another totally different set of properties, which means a second generation of loss of quality. This already does not make me surprised that you are seeing worse quality than you got with your AVCHD hybrid discs, including the blocky artifacts you mention.
Next, the change upwards of the bitrate will NOT improve the quality of the original. If the original was using VBR max. 16000 kbps, then that is as good as it is ever going to be! Silk purse and sow's ears spring to mind, I am afraid. That is not to say the original is a sow's ear in terms of quality. We both know that your original video is high quality high definition. But my point is that you can't make it *higher* quality than it already is. Video doesn't work that way -- and if you are processing it multiple times, being mpeg, you *lose* quality, rather than improve it... So essentially, you should leave the original bitrate alone, whatever it was.
Next, is the field order. Your original is Upper Field First. And a basic rule of video editing is that if video starts off UFF, it must remain UFF (unless, depending on the circumstances, it is converted to progressive scan/frame based). If it becomes Lower Field First, you have reversed the order in which the eye is seeing the interlaced frames. And that of course means your eye will be seeing things incorrectly which the brain interprets as lower quality and more often than not with 'jaggies' and blocky artifacts, especially in fast motion, panning shots and where there are strong vertical lines in your video.
Now, AVCHD video is completely compatible in its own right with the international Blu-Ray standard. It does not need to be converted to the Blu-Ray format to be burned to a Blu-Ray disc. The BDMV file structure you get on hybrid DVDs is the same as you would get on a Blu-Ray disc when inputting AVCHD files.
So if you have created your new file(s) in the Editing module and they are AVCHD (which they are), then you Share > Create Disc > Blu-Ray. And when the burning module opens, you manually insert your new AVCHD files. Then in the middle icon in the bottom left of screen, you make sure the 'Do not convert compliant mpeg files' box is ticked. That way the AVCHD files should be burned with their original AVCHD properties, and not be converted, as they obviously have been, according to the properties which are set out in the bigger top window in that icon.
