Multilanguage: CB Login goes to wrong language

I'm using the FaLang component for the translations. Which seems to work fine apart from this part I guess.

Is there perhaps a way to do this with auto actions?
i.e. get the current language from the URL and use that to redirect them to the right page after login?

I've no idea how that component works so I don't know what your needs are. Do you need to redirect to a specific URL with a language tag in it? For example the following.

example.com/en/login

The above is the format Joomlas language filter uses. If you need to redirect after login to a specific URL format you can just specify your URL within the login redirect parameter of your CB login module. I suppose you could use CB Auto Actions for this as well if needed, but shouldn't need to. Ideally your language extension should act on the after login Joomla trigger and act on it accordingly (CB fires Joomla trigger in addition to its own triggers).

The FaLang component also works with the language tags, like Joomla does. How exactly it works I'm not sure, it has been build up from the older Joomfish component and updated to work with J2.5 and J3.

I have set the specific URL like you said in the CB login module and with FaLang I made a translation of the module aswel including a different URL, which works correctly when you login using that actual module.

But it doesn't seem to use that URL when you are prompted with the login, as described earlier.

I agree that the Language extension should do this correctly. But I would still like to try this with Auto Actions, that seems a shorter route than having to finding and setting up another Language component.

Could you explain to me how I can take the current language tag from the URL with Auto actions and apply this to a redirect?

But it doesn't seem to use that URL when you are prompted with the login, as described earlier.

The CB Login page uses the parameters of the first CB login module it finds. If you've multiple CB Login modules you'll need to find the one it's loading and add your redirect URL to it. You could also use CB Auto Actions with a Redirect action on the after login trigger. You also could be landing on Joomlas login page and not CBs. Ensure you've our free CB Core Redirect plugin installed to prevent this.

Could you explain to me how I can take the current language tag from the URL with Auto actions and apply this to a redirect?

You'll need to turn off SEF and see what the variable is in the URL. You can then substitute it in (e.g. [get_lang]). All substitutions prefixed with get_ pull from the URLs variables directly.