Hi Peeter,
Sphinx community is way too small to have any people how are dedicated to work there, so you need a lot of luck to find an expert you can hire.
Sphinx templating is based on Jinja engine which is the same what Django is using. Anyone who can work with Django HTML websites will be able to learn to work with Sphinx.
That being said and after done some templating work for my own company, Sphinx templating especially with autodoc is difficult to work with, mainly due to lack of documentation, examples. Expect to spend a week or two just for the learning curve. For individual questions, this mailing group is good.
Some starting pointers
Br,
Mikko