優品 is yuhin and is one of the several praisewords on higher level swords and means it is a superior item. They I think decided to translate this as "well-made" which doesn't have the same impact that it otherwise should.
"Nagayoshi" should not be used, you should instead say "Chogi."
You can call Kanenaga "Kencho" and it is probably better to do so. If the condition is superior you can think about submitting it to Juyo. Kencho is more than sufficient as an attribution to pass and any good Kencho you find you should be able to think about that. He has a Jo-saku rating but I have seen many Kencho that were better than Chogi attributed blades. Some are quite stunning. The reason for this is that Fujishiro seems to have judged him a bit lower than he is otherwise judged.
In terms of how he is handled at Juyo and Tokuju he is more like Jo-jo saku. That allows for his best work to surpass the weakest work of Chogi which is fact by looking at the blades.
The sayagaki is ambiguous, in the reference to the Chogi group and I don't think they translated the last part of it as there is a reference to "naka doku" (middle / this smith) coming after "Chogi group". I would pay Markus Sesko to properly translate it.
I think he is saying that the hamon is representative for this smith and the Chogi group. What that means is ambiguous as it could mean that he feels it is a work of Chogi or that it could be Yoshikage or Nagamori. So it may mean a bit up or a bit down from Kencho. The fact that it has Honami Koson shumei on it is not necessarily helpful. If Koson has expressed an opinion which is acceptable without major argument it will be accepted even if a judge has his own opinions.
This is OK since there is no known correct answer to the question "Who made this sword?" Acceptable answers may be any of the smiths that I just named. Any two experts could agree that there are pros and cons to each of the answers. When one is established then it can be accepted as the same arguments could be raised about any of the other answers.
The main criteria is quality, does the attribution match the quality of the blade. If Koson thought it was better he'd have said Chogi. If Tanobe sensei thought it was definitely Chogi he wouldn't have done the sayagaki, instead he'd have written back that the shumei should be removed and the blade submitted to Juyo and reassessed.
So you can probably draw a line through Chogi as an appropriate answer, but you could laugh to your friends and say maybeeeee Chogi. But also maybe Nagamori or someone else in the group. All of that making Kencho an acceptable answer.
Note that once a shumei is on something they never put DEN on it but DEN can be an appropriate thing to add otherwise. Like if you wiped the shumei it might go Juyo as DEN Kencho but with the shumei it would pass Juyo as Kencho even if they think DEN. This is one of the peeves I have about how they use DEN.
Having a look at the sayagaki he didn't do backflips on the blade but he has confirmed it is a very good sword and if I received this I would consider Juyo submission myself. But I don't know how the blade looks. Bizen remember gets a bonus point always so you really need to show it to someone locally who has Juyo examples and try to compare against other Juyo works.