Detailed:
In Main, a sub load a layout with an EditText. Another module passes through Callsub2 a value to this EditText by the sub mentioned above. But I can get the value assigned to this EditText.
The sub in Main named Detail is looking for two Strings as the parameters. Your third parameter in your CallSub3 is Data, this should be a string or a string variable. You should log() the values of first and sec and see if they are sending the data you are looking for to the log. If the types are correct, it should work. Also, how do you get the module Test to run? It is not an Activity, so the Main must call it or a function in it, which in turn calls "Detail".
This is strange, looks like it should work. Look at your detail.bal file again and make sure the EditText field names are spelled right. If they are in globals and in the detail.bal file, try doing a Clean Project under the Tools tab.