This kind of detail is generally made available in the "what's new" text files that Safe publish on the download pages, like this one for the beta:

http://downloads.safe.com/fme/beta/whatsnew.txt

In here you'll find that the TopologyBuilder has been the subject of quite a lot of effort with 13 updates and fixes by my count. Here are the first 5 and the builds that they feature in:

========================== BUILD 16127 20151110 ==========================
TopologyBuilder: Fixed bug ordering closed arcs around nodes (PR#65451)

========================== BUILD 16112 20151019 ==========================

Transformers: Use terms edge/face rather than line/area for
topologybuilder output (PR64057)
TopologyBuilder: Fixed bug rebuilding a donut from a self-intersecting
polygon (PR#46199)

========================== BUILD 16102 20151002 ==========================
Transformers: Update terminology in topologybuilder and make a single
input port (PR64057) (PR63268)

========================== BUILD 16098 20150928 ==========================
TopologyBuilder: Added option to automatically deaggregate input and
rejected port (PR#47509). C80277, C80277

========================== BUILD 16095 20150923 ==========================
TopologyBuilder: Fixed crash for rich input and a maximum number of
coordinates (PR#64138). C22633

I'll further add that in FME 2016.0, the topology engine has had huge improvements in robustness, particularly in the realm of topology computation involving arcs. But all versions of the transformer will get those robustness fixes.