An All-In-One solution would be
SubtitleCreator.
As told you in the German forum, there is some work involved.
Frankly I do not see the reason why one would use TAW if only subtitles/audio have to be added/replaced/deleted and NO MENUS should be changed/edited/added/removed.
The cells IDs (CID/VID) may be edited, added, reordered, even moved (a CID must be associated with an existing VOBU) without reencoding the video, but the trouble is that no software I know can do this. The easiest way is to reencode the video, with chapter marks, which would direct the encoder to place CID/VID at those positions.
Use the sticky of adding subtitles/audio to existing DVDs with menus and live happy.