Maybe a little bit late, but better late than never:
LucasChess uses the 1.51 version of the DGT driver. The sounds for move announcements are not included, as you noticed. However, you can still download and install them from the DGT site: http://www.digitalgametechnology.com/index.php/support1/dgt-software/unsupported/driver-1-x/move-announcements
Restart LucasChess and move announcements will work!
I just set up Lucas Chess. I really like it, but have not been able to set it up for announcing moves when using a BT/USB DGT eboard. The DGT RabbitPlugin has a sound option, which works fine with other programs. However, Lucas Chess definitely does not use the DGT RabbitPlugin - I know, because only when I disabled the RabbitPlugin would Lucas Chess connect to the DGT board. The custom plugin for Lucas Chess has the DGT logo on it, so I think it must have been coded for by DGT, for activating from within Lucas Chess. However, under sound, move announcement is disabled. There is a button to "download sound schemes" from the DGT website - but those files are nowhere to be found (at least by me). Has anyone been able to have moves announced using a DGT board for input of moves in Lucas Chess? If so, how? Thanks! Mike Miller a/k/a kerpa