If we have opportunity to export and import word list on our symbian devices so why not to create an Pc editing tool for that adding and deleting new words would be simple.
Interesting point. there is this option already. you can use notepad to edit words. But you need to know how to use it. if you want to add words, just write it on a notepad save it, copy it on the phone, then use custom dictionary to import the notepad file. It will add the word. If you want to edit existing word in the custom dictionary, you can't. I agree its complex, but for now you can modify the words on pc till they make a software for it. If they do it.