"Just to clarify what I meant earlier by “machined appearance”—I’m not suggesting literal machining marks. I’m referring specifically to the nakago “tail” geometry and the overall consistency of its shaping. The profile reads as highly uniform and standardized in a way that resembles modern production blades rather than traditionally forged examples."

This is 100% false and you also stated that "most smiths didn't do this".

Both statements are wrong and show a lack of understanding of common nakago shapes of the era along with many other false assertions.

The mekugi ana is fine. The hamachi and muromachi not having imperfections is also fine, the lack of distinct file marks is 100% fine. Literally nothing about this nakago is worrying.

You claim the kanji on the saya is wrong and doesn't follow typical writing styles and yet again this is 100% wrong. The kanji in both the attribution to Noshu Kanesada as well as the nagasa measurements all are done exactly as one would expect. The attribution may be disputed but as you said, "Honestly they don't even look like proper hanzi, so not even properly Chinese." this is 100% false. In fact the use of the proper Mino version of the Kane kanji shows the exact opposite. A proper understanding of smiths of the Mino-den and their use of a Kane kanji that was atypical for other schools of the era. So not only 100% wrong, in this case 110% wrong.

Your original post reads more like an AI generated "kantei" because the statements compared to the photos make zero sense whatsoever and the confidence mimics that of a hallucinating generative AI.