I just downloaded a 6GB 1080p WEBRip of the Open-Matte version. It has hard-coded Russian subtitles at the bottom-middle of the video for locations and the Hawkeye in Japan scene (unlike the stylised subtitles for the home and theatrical releases). I have the 4K SDR WEBRip (theatrical aspect-ratio) with zero hard-coded subtitles (even the stylised ones).
I figure, a combination of the 1080p blu-ray and Open-Matte WEBRip, and the 4K SDR WEBRip, they could be used to improve video quality of the Open-Matte release, and perhaps remove foreign subtitles in the Hawkeye in Japan scene.
Bluebird released a 30GB Open-Matte for Infinity War using blu-ray footage some time ago, but it still had hard-coded Russian subtitles accompanying the English location names. It was probably not possible to disguise cos the text is at the top which is from the Open-Matte.
I don’t have the time or and skill to 100% match the higher quality footage to the pixel and frame-by-frame. I assume Bluebird will attempt it eventually, it just might take several months to a year for a release.