I'm not aware of anything using this attribute and I think it has more issues than it solves, so I think it should be removed to simplify things.
Right now, we have to pick between transliterated and translated. This is often difficult for Japanese releases (both Japanese originals with Latin pseudo-releases and English originals with Japanese pseudo-releases) because many of those releases contain both transliterated parts and translated parts. Japanese releases are the primary place where we use this relationship type too.
In other cases, it's neither a transliteration nor a translation, such as when the titles contain multiple languages and the pseudo-release titles are just shortened by removing one of the languages. Removing the attribute doesn't exactly fix that, but it avoids the need for explicitly choosing between "transliteration" and "translation".
The attribute is also not very useful, since it provides no useful information on its own - you have to consider the language/script attributes of the releases to find out whether you should use it. E.g. if you're a monolingual English speaker who doesn't know any other scripts and you're looking at a Japanese release, if the options are a transliteration into Latin script or a translation into Korean, the transliteration better suits your needs. If, however, the options are a transliteration into Hangul or a translation into German, the translation better suits your needs. If you're considering the language/script anyway, you don't really need the attribute.
In a similar way to my suggestion in
STYLE-393, we could just use "transliterated/translated" where we currently show the attribute.