Correction: because of a symlink I used for my current TS dir that has no counterpart for the old TS dir, I was specifying a non-existent path when testing the old directory...
So, FG does start with the old TS dir in --fg-scenery when TS is disabled, and it does have the LFLL buildings in this configuration (which was not the case one or two months ago, when I started to write in this thread). However, when I enable TS, FlightGear can only pass the "loading scenery" stage if I use the new TS dir for --terrasync-dir. With the old one, there is still the apparently endless loop with spinning little bar (even with --prop:/sim/terrasync/svn-server=http://ns334561.ip-5-196-65.eu:8888/trunk/data/Scenery/).
I maintain the 8080 vs. 8888 statement from my previous message (after trying to update both TS dirs), although I don't see any consequence from end user POV.
Sorry for the confusion.