As the sword will be judged differently by men of different interests, you must be very careful in its selection. Some are foolish enough to pass judgment on a sword which they cannot really understand, others will not speak the truth although they see it.
The merchant may speak falsely in order to sell his wares.
If a blade belongs to some nobleman, or if it is appreciated as a family treasure, or if the possessor is very proud of its supposed qualities, the true judgment will often be withheld through courtesy. When you would have any sword truly judged, you must commit it unreservedly to a judge of absolute sincerity.
— The Complete Manual of the Old Sword (ca. 1793)
Nothing has changed.
Bear in mind there are some transcription errors. Since it was translated over 100 years ago there is some Olde Tymey romanization as well. I find these old books fascinating as sometimes they confirm things that took us a long time to get to. For instance, this book relays the story of Niji Kunitoshi changing his name to Rai Kunitoshi at the age of 38 and names him Magotaro.
With the most useful data we have now, the last signed and dated Niji Kunitoshi is indeed at the age of 38 and the first signed and dated Rai Kunitoshi blade appears at age 49. Until Tanobe sensei put the lid down on this theory, there was a lot more belief that these were two separate smiths. Rai Magotaro Saku is also on a blade which is now Kokuho (National Treasure) and attributed to Kunitoshi.
Sometimes the old books have truths in them that were forgotten, and in the meantime people came up with some new fanciful stories. Not everything in an old book is going to be agreeable. They are however important things that fill in the gaps or at least provide some fertile ground for modern analysis.