Could be possible use some text to speech api? So any other language would be support, if we use the google translator API like TataruHelper do in FFXIV. https://github.com/NightlyRevenger/TataruHelper

I would also like to bring up this suggestion as well. Would make it extremely easy to use the TTS voice of our choice.

I also maintain versions this addon for German, Spanish, French and Russian. You can find those on CurseForge.

Is there another language besides these five you are looking for?

Portuguese-Brazil... I've started a project today https://github.com/vinicius83/BigWigs-Voices-PT-BR
Other side is done, I tested it and the sound is too much low, with my spells files (ogg) and with the spells in the english version...

I've been trying to tweak the settings... but still low.. in the big wigs settings says "loud" lol ...

The sounds are played through the Master channel, so if the sounds are too low, increase the Master volume and lower the other channels.

Have you seen the new text to speech feature on the 9.1 ptr? It can use voice options that are on the user's computer and it is super easy to use. I already messed around with it a bit and you can make it say anything it isn't limited to reading what is in chat. I made this on the ptr today and it was working perfectly.

SlashCmdList["TALK"] = function(msg)
    -- Name = "SpeakText",
    -- Type = "Function",

    -- Arguments =
    -- {
    --     { Name = "voiceID", Type = "number", Nilable = false },
    --     { Name = "text", Type = "string", Nilable = false },
    --     { Name = "destination", Type = "VoiceTtsDestination", Nilable = false },
    --     { Name = "rate", Type = "number", Nilable = false },
    --     { Name = "volume", Type = "number", Nilable = false },
    -- },

    local voiceID = TEXTTOSPEECH_CONFIG.ttsVoiceOptionSelected
    local destination = Enum.VoiceTtsDestination.QueuedLocalPlayback
    local rate = TEXTTOSPEECH_CONFIG.speechRate
    local volume = TEXTTOSPEECH_CONFIG.speechVolume

    C_VoiceChat.SpeakText(voiceID, msg, destination, rate, volume)
end
SLASH_TALK1 = "/talk"