There are several kizu/kitaeware flaws on the blade and they are visible through the images. However, I can tell you that there is no serious flaw. Considering the history, current conditions are quite natural and tolerable.
This blade was forged in the Nambokucho era, over 600 years ago. It has a rich history and compared with other swords with the same tachi, it is natural. The Hamon and the Boshi are clear and the faint Utsuri is visible. In hand, this blade appears to be mature and robust.
This answer was in response to a question about the partially erased Kikumon/Ichi:
It is not a Kikumon, but someone probably engraved Kikkumon and ichi to try to be recognized as a Kikugosaku.
Kikugosaku swords mostly became national treasures, which were forged for the Gotoba Emperor in the early Kamakura Period. I think the style and shape of the sword resembles that.
Later, it appears as if someone tried to grind the non-legitimate Kikugosaku, but you can still see a little of the symbol.
NBTHK recognized it as Mumei and not Kikugosaku.
That answers all the question for me NOT buying the sword. Why go any further in picking it apart?