Maybe those links have little SEO value but in the other hand, if you really help on specific forums, you have potential clients there. It all depends, let me explain:
We had this experience with Spanish forums about joomla (we don't use joomla anymore). My partnership helped other people never thinking about SEO or whatever, just helping about things that she know that she was ahead of others and giving right answers. Our experience was that some people just tried and failed to create his own website with joomla and then, searching about it on forums and google, to find help, found our answer and thought, ok, this person knows it better than me, so I'm gona hire her.
So I don't think you wasted your money, it all depends on the focus of these forums, at least, our experience was good, and we never expected it.
