Okay, I know I'm gonna get a lot of hate for this, but I need to ask something: Would it be wrong to have a fan translated game that has voices have a fandub in a specific translated language made? I mean yes, I know some people want to keep the authentics of Japanese voices because it's their "preference", but 1. I'm sick and tired of purists jamming "Japan voices only and/or raws, deal with it" attitudes. And 2. because if there were some people who wanted to experience the game in complete English on their own choices, the Japanese to some people just doesn't quite fit. That's kind of how I feel with the Utena Saturn game when I played it. I mean I like that it's got the text translated, but when I tried to listen to the voices...well...none of them clicked very well. I wouldn't mind that some of the Saturn and PS games that had translations with no voice alterations have the fandubs, but I know nobody will ever want that because like I said, purists hate ANYTHING dubbed.
For the most part just ignore the purists. There are some merits in some cases, in other cases much ado about nothing, in other cases I would say purist notions actively ruin things (usually when "nothing must be touched" means you effectively end up with 60%+ of the text effectively being proper nouns), and any amount of subjectivity, to say nothing of the general three way tug of war between the liberal, literal and pizza cats approaches to the world.
Anyway there have been a few fan dubs of things. Golden Sun voice acting experiment being among the more notable of these.
The trouble tends to come in getting people with decent audio setups, decent voices and the like to come together to do things.
On the flip side voice synthesis and replication is getting amazingly good -- I have long toyed with getting one of those neural net voice faking (deepfakes if we are using the parlance of the kids) things trained on say the top 500 actors (training data for something actually quite good is really not a lot of talking at all, easily something you could get from the average film, something bad but still enough scam people that know you out of keys to bank accounts over a phone an awful lot less) on your chosen database and seeing what could be done for fan edits of films. Would be nothing (beyond issues of playback and storage space*) to in turn apply that to games.
*could go the utter heretic path of have an emulator featuring lua scripting call the relevant voice clips, or maybe even text to speech on the fly, or possibly have things dynamically narrated like Bastion.