>>281401232
Anime largely gets translated because there exist distribution networks for it. Distributors primarily only focus on anime because the medium is easily digestible and easy to work with. There's a video channel where you can put your translations right in front of someone, the timing is already corrected, with visual cues to assist in that. Licensing is also a sorted out issue now.
Working with drama CDs is a pain in the ass by comparison. For starters, Drama CDs are often released and licensed by a record label separate from the production firm. There are also fewer avenues for distributing audio - especially before streaming platforms, printing a line of CDs was a lot more expensive than dubbing a VHS tape, and while video rental was extremely popular, there weren't nearly as many places you could just rent a CD. This was before any secondary merchandise outlets had really reached the US. And even if it did get licensed, translated, and put to market, as anons ITT have mentioned there's the trouble of actually consuming it. You just read a script insert and listen to voices in a language you don't understand without any visual cues. It was never really a simple or desirable thing to try and push overseas.