So I examined these files with dbPoweramp and Mp3Tag and found MC wrote garbage into those tags. Grrrr.
MC didn't put garbage into the tag. It put a number that represents a date into the tag, and you didn't tell dbPoweramp or Mp3Tag that it was a Date tag. Hence, they showed the unformatted data, while MC showed the formatted data, because MC knew it was a Date tag.
Try this;
In any Audio View you like, add a column for [Date Imported], which should always have values in it for you to see. Right next to that add an Expression Column, perhaps name it "Raw Date Imported", then for the expression enter [Date Imported,0], which means show the raw data in the field. Now compare the two columns. Both are using exactly the same source data. The "Raw Date Imported" is showing the raw number that represents the date and time. The whole number represents the day, and is that many days after a reference start day, and the decimal represents the time, as a fraction of a day. The "Date Imported" column is showing the formatted data.
The number used to represent dates in all applications is base on day zero being 31/11/1890. You can see a perfect example in one of your images. You entered a DATE(RELEASE) of 1973 in mp3tag, which you didn't tell it was a Date tag, so it just stored the number as is. When that tag was viewed in MC, which knew that the tag was a Date tag, it displayed it as 5/26/1905... which is exactly 1973 days after the reference (starting) date used for Date tags.
Check the day count on
https://www.calculator.net/date-calculator.html?today=12%2F31%2F1899&ageat=05%2F26%2F1905&calctype=diff&addendday=1&x=53&y=11.
The "Release Date" is a very common tag in most applications. MC usually works out what the date is during import, or metadata updates, and puts the value into its [Date (release)] field, even if the field is named something else, such as "Date Released", or "Release Date", etc. Stop trying to manage tags outside MC with other applications. It will be less confusing.
I'm sure if you Googled around you would find lots more information. MC isn't broken. It is working correctly, and as per the standard conventions.