I was able to reproduce this problem with both Tor Browser 4.5.3 and 5.0a3 on a Mac OS 10.8.5 system. Dragging the fav icon from the tab to the Bookmarks Toolbar does result in the page title being used.
Yes. I just tested in 38.1 ESR and in a 40.0 beta. As another experiment, I tried disabling Torbutton in TB 5.0a3 and found that this bug disappeared: the page title was transferred to the Bookmarks Toolbar. I did notice that the fav icon was missing, but that also seems to be the case if I use Cmd+D or other methods to create the bookmark.