It's working now!
When he made the modifications I mentioned before, he already fixed! Just doesn't work because I had a cache of the previous version. I cleaned
docker run --rm --name subliminal -v subliminal_cache:/usr/src/cache -v /var/media:/var/media -it dtroncy/rpi-subliminal cache --clear-subliminal and now it working!
Thank you very much Iridium for helping!
For the record:
For install it you need docker first Add-ons > Install from repository > LibreELEC Add-ons > Services > Docker
and after just need to do docker pull dtroncy/rpi-subliminal
This is how I use it on cron for searching for subtitles, in just one provider, in pt-BR language, at every 6 hours: