RasaNLU for Intent Recognition handling slot synonyms

Hi, I have the following problem.
I’m using RasaNlu 2.0.0a2 for Intent Recognition and training process is working fine for all sentences in the .ini file and also for all slot values even if I use slot alternatives like (den | playroom | downstairs).
But in case of using slot synonyms by using substitutions “(den | playroom | downstairs):den” RasaNLU will not take care of this slot synonyms after pressing the “Train Button” in the Rhasspy GUI and the nlu.md file is created without any synonym entries.
So maybe I have missed something, but in my opinion there should be an entry from NLUIntent where I can see the expected output (in this example “den”)
Thanks in advance!

Someone has an idea?