I am editing an old file set up by another firm that is used by our clients to keep track of room sizes etc, which has a room data table and room tags tied to area polylines. It has worked just fine on our 2013 Acad Architecture, but when I sent them (saved down to 2010) back to our client, using 2012 Acad Architecture, the tags disappear and the table is unpopulated.
It seems like it must have something to do with the file originally being created way back when, along with some quirk between 2012 and 2013. I have attached one of the files as an example.
AutoCAD Architecture objects do not save back across different file formats. There was a new file format with the 2004, 2007, 2010 and 2013 releases. The 2012 release uses the 2010 format; when you open and save a 2010 format file with 2013, the AEC objects therein are upgraded to the 2013 format. At that point, you cannot save the file in a way that will allow it to be opened in 2012 with working AEC objects.
Assuming that your client is going to stay with ACA 2012, you need to be using ACA 2012 (or 2010 or 2011) when editing the file.
(Yes, ACA provides the ability to SAVEAS to the 2010 format, but the AEC objects inside will be seen as "future" objects when opened in 2012, and the AEC commands will be disabled.)