Are translation journals still a thing? In the second half of the 20th century there were a large number of English-language journals published in the West that carried only translations by Western academics of Russian-language articles.  The original versions of these articles were written by Soviet academics and had appeared in Russian-language journals published in the Soviet Union.  The English journals were commonly known as "translation journals" (not to be confused with translation studies journals, which are about the art and science of translation).  Perhaps the most famous translation journal was Soviet Physics Uspekhi, though Physics Today once listed sixteen further translation journals published by the American Institue of Physics and associated societies, and there may have been many many more in other scientific fields (and humanistic ones too, for all I know).

Were such translation journals unique to the Cold War, or do they still exist today?  A successor to Soviet Physics Uspekhi is still published today, under the name Physics-Uspekhi, but I think it operates quite differently and for quite different purposes nowadays.  In particular, its editorial office is in Russia, not in the USA, and it seems that it is Russian academics (possibly the authors, or someone working at their direction) who are supplying the English translations.  So rather than serving the interests of English-speaking academics who wish to discover or disseminate the work of their Russian-speaking counterparts, the journal today seems to be serving Russian-language academics who want to bring their work to a wider English audience.

Are there any scholarly fields today where a lot of research is being published in non-English journals, where these articles are being routinely translated into English by translators unconnected with the original authors, and where these translations are being published in dedicated journals?
In mathematics there are still regularly published English language translations of Russian language journals. Examples:


St. Petersburg Mathematical Journal 
Functional Analysis and its
Applications
Russian Mathematical Surveys
Transactions of the Moscow Mathematical Society


There are quite a few others.

For most (if not all) of these journals it is often now the authors themselves who supply the translation (I believe this was sometimes the case long ago, although various US professional societies organized formal translation programs, sometimes with funding from agencies like the NSF; the issue is that translating research articles requires substantial understanding of the content, and this greatly limits the pool of potential translators).

Here is a Japanese source journal:
Sugaku Expositions