Coincidentally in Canada there is also a music band who is called as «Liu Brothers» (by Chinese fans) or «Lưu Triplets» (by Vietnamese fans). They are Vietnamese-Chinese men but born in Canada. So the original text is called as «劉氏四兄弟» or «劉家兄弟故事».

https://tuoitre.vn/ba-anh-em-trai-dep-ho-luu-den-tphcm-568332.htm
https://vnexpress.net/anh-em-ho-luu-chung-toi-hanh-phuc-vi-co-nhieu-fan-viet-2877519.html

I remember really loving the opening song in this one... though I thought the rest of the film never quite matched it.

It always bugged me how the mice constantly change size relative to Leopold in this. Especially at 6:20 when they suddenly become really huge!

This movie, after some consideration, I decided not to translate. Those are just rambunctious discussions at the dinner table, so it is fine to leave them in Russian or English.

In my opinion, that is fine to leave most of it as is, just footnotes. However, fortunately characters "Veselchak U" and "chatterbird" have equivalent words in classical Vietnamese language : Tễu (笑 / "laugh" ; who has a cute body and funny personality), Liến Thoắng (連通 / "continuous communication").

https://tve-4u.org/threads/alisa-phieu-luu-ki-kir-bulychyov.36569/

Nice book! Thanks for that link.

Yes, I found it hard to translate as well. But if you're trying to do it, I think you should use the latest English subtitles that are here, rather than the older ones elsewhere online (a lot of which have mistakes).

By the way, regarding the names of the characters:
(Professor) Selezniov = slug
(Captain) Zelyony = green
Gromozeka = the root is "grom" (thunder), probably because of how boisterous he is
Veselchak = happy person (he's often smiling and eager to please in the film)
(Professor) Verhovtsev = higher
Ptitsa Govorun = talkative bird (I was fortunate that English already has the word "chatterbox", which I could easily modify into "chatterbird")
Glot = possibly from "glotka" (throat)

Most of these I kept as is, but I did translate "Green" because that's a common English surname too.

I have watched this movie on Vietnam Central Television (VTV1, "The Little Flowers" program) since I was very young, of course only on black-white TV. This is a very challenging movie about translation. Here is the film story (фильм-сказка) : http://www.barius.ru/biblioteka/book/852

I have watched this movie on Vietnam Central Television since I was very young, although I did not know the name of the movie at that time and only watched it on black-white TV. However, the child's brain remembers the fanciful scene in the circus for a long time, so it will surprise you when you watch it again later. That, I think, is the psychological success of the filmmakers.

I feel like the tricksters in this film (or someone much like them) appeared again a year later in Nataliya Golovanova's excellent "Sweet Porridge". Which is odd, as the two films share no crew except for two animators (Aleksandr Dorogov & Violetta Kolesnikova) and the script editor Tatyana Paporova.

Sometimes there were "borrowings" like that in Soyuzmultfilm at the time.

The fact that they leave the planet so readily at the end suggests to me that the cutthroat capitalist mindset had not yet penetrated very deeply into Russia. Which makes a lot of sense, as the story was written in 1977. The faces are American, but they sure don't act very American!