BuddyPress.org

Re group name length: I was just guessing, since I cannot duplicate the error.
‘Vanhat talot’ is short, so that shouldn’t be the issue.

So you created a group – and the id was 0, correct ?
Then the next group failed due to the duplicate entry 0, correct ?
If so, then the group id field is not being auto-incremented.

The enable_forum field should be 0 if you did not select ‘I want a forum’ when you created the group.
If you did select ‘I want a forum’, which version of bbPress are you using?