I would guess that if it were possible to convert testes to ovaries, they wouldn't be fertile and would only be useful in producing estrogen. Natal women are born with their ovaries containing all the eggs they will ever have. Seems unlikely that eggs could grow after testes are fully formed.
On a related note, I met with a fertility doctor to store sperm and he told me of new research that is making progress towards a technique that could allow for male genetic material (from sperm) to be put into an egg, then to have the egg's DNA removed, thereby making an egg that contains only the sperm's DNA, which could then be fertilized by a male partner's sperm (which would then be carried by a surrogate). He said it was very early and if it ends up being possible, it would be about 10 years out.