Web transactions in EGL are a holdover from VisualAge® Generator, and offer a very basic web interface for user I/O. Best practice is to use web transactions for migration only. New code should use JavaServer Faces (JSF) or Rich UI for a web interface.
You can customize these JSP files using Page Designer (see Using EGL with the Eclipse IDE).
EGL does not just allow you to modify the JSP files that it creates from your VGUIRecord files; it takes for granted that you will heavily modify these files. For this reason, EGL does not overwrite an existing name.jsf file (where name is name of your VGUIRecord). Instead, if name.jsf exists, EGL creates (or overwrites) a file named newname.jsf. You must copy the changed portions of the file to name.jsf yourself. Alternatively, if you want EGL to replace name.jsf, delete the file before generating.