I don't use the translation tool myself so I cannot comment on that but I can say that I've manually converted a number of apps over the years. If you have hundreds of forms then you may want to pursue why the conversion isn't working but if you want a solution that would allow you to do the conversion *now* then I'd recommend starting by manually updating one or more forms manually as outlined below:
1. View the form in the editor and press ALT-F12 to shown the DFM.
2. Search/replace TPanel for TsPanel (for example)
3. Press ALT-F12 to show the form, then F12 to show the code.
4. Press F3 to repeat the search and replace.
5. Repeat steps 1-4 for each control you want to replace.
6. Click Save.
You can either update all of your forms manually or once you're comfortable with the process you may prefer to use a global search and replace. You will need however to open each form in turn and allow the IDE to add the AC units to the uses section.
Good luck!
Regards,
Hamilton