Help rendering render 1440x1080 properly

I think my overall workflow plan got a bit lost; Averdahl & I are approaching differently. (Averdahl's approach is objectively more efficient & technically correct, but I am also confident mine would work.)
So I am going to sort of start from scratch and list out how I think you can solve:

Before doing anything else, run that short "00000.MTS" file through Media Encoder (not Premiere!) using that preset I had sent (1440x1080 to 1920x1080 ProRes-Progressive.epr). You should have a clean-looking ProRes version of that raw clip. If not, then the rest of my post is not going to work for you. But assuming it looks good...

1. Run all of your raw footage through Media Encoder using that preset I had sent. You'll get some big files from this, make sure you have appropriate storage available.
2.  Either change your existing sequence settings OR create a new sequence with settings as follows:
   (Previews can be whatever format you prefer, but make sure the size is 1920x1080)
3. The newly transcoded ProRes clips are meant to replace your source footage. So if you have changed your existing sequence, you'll need to replace all your MTS clips with the ProRes re-encodes.
   If you are creating a new sequence from scratch, you'll have to rebuild your edit. I recommend creating a new sequence just to eliminate as much error as possible.**
4. Export using the Match Source - Adaptive High Bitrate Preset.
5. You should have a good-looking final file.

As I alluded to, this is almost certainly not the most efficient way to handle this type of footage. But somewhere, settings are getting lost, so this is the most straightforward way to solve that I can come up with. As a bonus, the ProRes stuff should also be much quicker to work with since its all-i. Good luck!!

**I'm only recommending this because it sounds like you're just adding a graphic opening/closing to this, and there aren't many/any edits.