I just tried the extension in my MW 1.27.0 installation and when I tried to save my first table, I got an SQL exception. Some googling led me to https://phabricator.wikimedia.org/T120791 which suggests replacing the methods begin()/commit() with startAtomic()/endAtomic() respectively. I replaced them in the DataTable2Database.php file and the extension worked fine (I haven't tested all the features though). I would commit the update myself, but it's hosted at SourceForge where I'm not confortable. Could someone else take care?