According to this Babylon support article, Opera is included among the products in:
Babylon does not recognize text well in a specific application I am using
The "workaround" suggested is :
Type the words you wish to translate manually into the Babylon window.
So I'm sorry to say that this problem is probably unfixable.
One can only hope for improvement with future versions of Babylon.
In the meantime, maybe copy-and-paste will be a solution.