Can't select dutch language in

I just installed a fresh Code docker container. I opened one of my document to find out I can’t select “dutch” as language in the “format cells” dialog. Is this a known issue? I added “nl” to available languages, but thats the spell-checking I guess?

I use Code from Nextcloud. I always keep my language on English. If I switch the Nextcloud language to Dutch, the default language for the cells is set to Dutch, but the numbers in the Cells are not formatted to Dutch.

I use a docker compose solution with the following environment variables:

server_name=
DONT_GEN_SSL_CERT=true
cert_domain=
extra_params="--o:ssl.enable=false --o:ssl.termination=true --o:logging.level=warning --o:num_prespawn_children=8 --o:mount_jail_tree=true --o:per_document.max_concurrency=6"
dictionaries=nl,de_DE,en_GB

Hm, configuring the settings in a custom coolwsd.xml does work. So, maybe something is wrong with using the environment variables? It came from the documentation…