Perhaps, to speak in a language that your character knows, but you don't, you could type a command and then the message. So, for example, you could do "/elvish Hello!", it would appear as "(username): Elvish: Hello!" For people who knew the language, but for others it would translate it into the elvish language somehow using an English to elvish translators, like this: https://lingojam.com/CommontoElvish(D&D)
Perhaps, to speak in a language that your character knows, but you don't, you could type a command and then the message. So, for example, you could do "/elvish Hello!", it would appear as "(username): Elvish: Hello!" For people who knew the language, but for others it would translate it into the elvish language somehow using an English to elvish translators, like this: https://lingojam.com/CommontoElvish(D&D)