I think is not necessary have professional translators. Many projects use collaborative translation tools, and the results are good. In my opinion the important is create a good community to support the project. I don't know the Woltlab balances, but I think it's a small company. The price of their products is fair, and I don't have any problem to colaborate translating to Spanish.
About a Spanish translation...
I sent an email to Woltlab and they provided me access to their products (Thanks!). I'm going to share my translation on Github to try to do a collaborative translation (I have permission to share on github all xml files and for use a free licence). I am Spanish native but I also have some technical questions (I don't know translate all terms and is not necessary translate all words). I think with colaborative translations is possible do good translations: asking and learning from other users.
Maybe is a good idea move all posts about translations to a new thread in General Discussion section? I think is a good discussion thread, but not related with this topic. (cc @Alexander Ebert)
The price is fair, but buying each official addon to translate it represent a budget. Plus the translators don't have any help. Nothing about modifications concerning variables, and it's a lot of work on our free time. I translated wBB 3, restart from the beginning for the 4 version, and it's necessary to restart from the beginning for the 4.1 version because there is a lot of change. Personally I stopped, too much cost and time for nothing.
Maybe the team need to change their political on these points.
Anyway, the product is good, and I thank them for their work.