One thing that would make the Apertium online user experience nicer would be source language detection. Edit the new web page design so that when a user types in text in the source language box, some javascript magic happens and it guesses the language of  the input text.

There are many libraries that do this. You can start by looking at:

https://github.com/tomayac/language-identifier

But there may be better ones.

For further information, join us on IRC: irc.freenode.net #apertium