Hey Arthur,
I've used the first script Aaron linked to and it is pretty easy to add new languages to the script. Basically you just add in blocks like this for every language you want after line 18:
{
Description: "Dwarven",
Sheet: "Language(Dwarven)",
languageSeed: 2,
characters: "Dwarven"}
For each one set the following:
Description --- what you want the language to be called
Sheet --- what you want the sheet to be called
languageSeed --- a value that will be used to randomize characters
characters --- which set of characters you want to use to make the gibberish version
Just make sure you have a comma after every bracket but the last language. You can pick from the four default character sets (what I did) and just change your seed around so each on looks a little different. Or you could add your own custom character sets by copying and tweaking what is there.
I'm actually using a different script in my next campaign that you might find interesting. The forum post is here:
https://app.roll20.net/forum/post/1112072/slug%7DIt doesn't have the same flair as the first but is a little easier to use (in my humble opinion). Just point it to an attribute that stores a list of languages each player speaks on line 2. Then they just use the command !speak [language] [message] (i.e. !speak Drow Die adventurer!) with their token selected and anyone who doesn't speak it gets garbled text.
It doesn't require modifying the script for each language and doesn't give away what language is being used as someone types a message by showing "Language(Drow) is typing..." at the bottom. It does require your players all use the same names for languages (Elven vs Elvish) and that you use the correctly in the command (I wrote a macro with a drop down for that in mine).
Just my $0.02 on the topic. If you have problems getting either to work post back and I'd be happy to help!