I wonder what the actual workaround could be (or if this is something the Discourse team has on their roadmap) for localizing group titles and/or descriptions.
I found some related information at How can badges and groups be localized (multilingual)?, but I just want to be sure before committing to it.
At the moment, custom group names, titles and descriptions can’t be localized with Content Localization.
The workaround in the topic you linked is specific to badges, so it won’t work for custom groups. Automatic groups are a bit different since their names and descriptions use built-in translations.
For now, probably the simplest workaround is to keep the group name as-is and put both languages in the title or description.