If I just had any clue how to fix that xD
I think it would be helpful to know if anyone else has these problems too, so that we know if it is a general problem or if I just did something wrong. Whereas I kindly deleted my lotrtw (2.08c) folder to have it newly installed by 2.0b and then 3.0, so I wouldn't be aware of any mistake by myself ...
I just checked those files. Interestingly nearly all .cas files in the models_building directory are younger than 2011, with only 2 or 3 exceptions that do not seem relevant, as none of them seems to be of elvish nature.
The descr_settlement_plan.txt file is also dating to the 9. March of this year, I think that should be recent enough.
Furthermore I found lotrtw-.cas-files from ~2008 in the RTW/data/models_building folder and experimentally deleted them, but it didn't fix anything... so atm. I'm really helpless regarding that matter...