Part of the issue is that many “complete” sets were made a while ago by members that may no longer be active, so they’re not getting updated as new movies come out.
Also, bear in mind that BR covers have different dimensions than DVD covers, so just swapping out the logo means your cover will be too short and maybe also too narrow(?) for a DVD case.
You are right, that’s why I went off of actual DVD cover dimensions, took the blu ray cover, and centered it on the template, then matched the excess area to the color of the cover, which thankfully was black. The more I think about it though, the more I’m thinking about it, the more I may just focus on I-VI matching covers, and let the Disney era stuff use the original covers. I have a folder of different covers, and I ran across something called “The Graphite Collection” and I kinda like the look of that. It also has matching covers for the Bonus Features disc and the 2D Clone Wars DVDs.