Given your handle, I am assuming that two cents from a lawyer may matter to you. I may be wrong in that assumption.

You are assuming that the labels put on these dates by Microsoft bear some resemblance to common usage of the terms. They are dates and times. They have some meaning if they haven't been fiddled with (but they can be fiddled with). The meaning they have is not what you understand.

I have many files where the modification date is earlier than the creation date. I have not fiddled with the dates and times, those were attached to the file by Microsoft Windows and Microsoft Word.

All of the others who have responded to you understand Word far better than do I. Believe them when they tell you that these dates have no useful function for verifying anything about a document. At best, they may provide hints. I find the Date fields very useful, especially the CreateDate field, but I do not trust them to tell me anything about a document.

Using Date Fields in Microsoft Word