The Tropical Fruit Forum

First flowerbuds on one of tarogayo seedlings.
Seeds sowed 2018.

Looks like Golden tribute is chinese marketing name for Haruka.
Pictures are identical, weight is around 200 grams and articles in chinese pages say both originated from citrus tamurana in Japan.

Yes, it is most likely  Golden Tribute Tangelo (黄金贡柚)
https://wapbaike.baidu.com/tashuo/browse/content?id=90920d34eb8bb2d8f053171b

https://youtu.be/-L2st96wSbU?si=Ujf9_6fJgzYj0pBX

Yes, it is possible.
In catalogue from C. A. Nobellius & Sons Nursery are cultivar names Seedless, Delicious, Twentieth Century.
In soviet import list from 1930 are also cultivars -
Delicious - they renamed-translated it as "превосходный" it mens Excelent, later when planted in soviet Georgia it got name Chinebuli ჩინებული, which means in georgian language the same word Excelent.
Twentieth Century
Seedless

because cultivars Delicious and Twentieth Century are in C. A. Nobellius & Sons Nursery Catalogue described as newly discovered, I guess, they mean that those are  culivars of australian selection.

Reading an old soviet bulletin from 1939, I came across cultivar called  Twentieth Century, imported to Soviet union in 1930.
Description: PCNA, big, round slightly flattened fruit up to 230g, or more. Deep red skin.

Can someone tell me more about this cultivar?

Definitely not a Kumquat.

There is a lot of discussion about ujukitsu,
I do not have Tanaka description, but I doubt, that Ujukitsu is yellow, pearshaped fruit.
Tanaka put it in one group with C.tamurana Hort.ex Tan. and C.luteo-turgida Tan. Which are definetly not pearshaped.
And according to: https://citrusvariety.ucr.edu/crc3467
"Notes from Dr. Bitters' 1963 trip to Japan: Average size fruit height 6.2 cm, wide 6.4 cm, yellow orange rind, globose,..."
Fruit in Riverside collection does not fit to description.

In japan pages Ujukitsu
written:
ウジュキツ
宇樹橘
うじゅきつ
or
ホウライカン Houraikan
looks like small orange:
https://www.kudamononavi.com/gallerys/view/id=7269

The first one is called thornless lemon or thornless Orange lemon.
無刺檸檬
無刺香橙檸檬
https://www.xn--hdst89am2b71ik9zca.tw/product-detail-900440.html
The second one is called papaya Orange
木瓜柚
https://news.ltn.com.tw/news/life/breakingnews/3013634

Some of your pictures show Sambokan, which is said to have been imported to Taiwan from Japan.
There is a lot of misinfo on web.
It is really hard to say what is Ujukitsu sweet lemon distributed to Europe from USA Riverside collection. They say it is a citrus ujukitsu, sweet lemon, in Taiwain identical fruit is called Sambokan, while in Japan, Sambokan is the name of citrus sulcata, which looks simmilar but is sour.

I had never tasted the New Zealand Lemonade fruit, but I have tasted the Meyer Lemon fruit and recently I have discussed a Ujukitsu from Taiwan compared with a Shiranui from Korea in the following video.

In my opinion Ujukitsu is an interesting variety, even if I would hardly consider it a lemon, it looks more like a big yellow Shiranui and it's very similar in shape to Kinkoji/Bloomsweet. It has a sweet pulp, there is no bitterness, just an hint of sourness (Meyer lemon is more sour and lemon-like) with an interesting balance, maybe more resembling oranges or pomelos juice but with yellow color and I think is perfect even just juiced. The fruit is a lot bigger than a lemon and even bigger than most oranges, it could have no seeds that is a plus in case you juice it. The rind is not very peelable, so it's more like a Pomelo, but the albedo is edible and not bitter at all, that is a great advantage compared to most of the lemons and more usable like the citrons for jams or candies.

It's easier to find more information from japanese sites using translator than in most of the english speaking forums, but it looks like it's a native variety of Taiwan maybe just named 甜檸檬 like Sweet Lemon in english, then brought to Japan while that island was under the empire rule, that is the reason why it is relatively famous in Japan too with Yuge Hyokan/弓削瓢柑/ゆげひょうかん name.

https://www.fruttama.it/forum/viewtopic.php?t=6910

citrus ujukitsu Ujukitsu, citrus yuge hyokan Yuge Hyokan and citrus ampullacea Hyokan are three different citruses.

Hello,
when you say, that there is no bitterness, to me it sounds like your tree is not Hassaku, but Hyuganatsu  日向夏.
Also, I see that some of the fruits form neck, It is more typical for Hyuganatsu than Hassaku.