Japanese doesn't seem to be getting initialized correctly

[hasamsote]

When attempting to generate Japanese text in the included WebUI using the docker CPU configuration (setting the Language: Japanese option), the voice fails to generate and there is an error in the log:

06:06:38 PM | ERROR    | tts_service:169 | Failed to process tokens: Generation failed: 
Failed initializing MeCab. Please see the README for possible solutions:

    https://github.com/polm/fugashi

If you are still having trouble, please file an issue here, and include the
ERROR DETAILS below:

    https://github.com/polm/fugashi/issues

issueを英語で書く必要はありません。

------------------- ERROR DETAILS ------------------------
arguments: [b'fugashi', b'-C', b'-r', b'/app/.venv/lib/python3.10/site-packages/unidic/dicdir/mecabrc', b'-d', b'/app/.venv/lib/python3.10/site-packages/unidic/dicdir']
param.cpp(69) [ifs] no such file or directory: /app/.venv/lib/python3.10/site-packages/unidic/dicdir/mecabrc
----------------------------------------------------------

This seems to be caused by failing to properly initialize unidic, which I fixed by going into the container with docker exec bash, entering the venv in /app/.venv and running
python -m unidic download
which downloads about half a GB of I guess Japanese dictionary files.
This step should probably be run during setup of the container, but I'm not sure where exactly.

The system is Fedora Linux Server
kernel 6.18.3-200
Docker version 29.1.3, build f52814d454