How secure is a pronounceable password in terms of entropy?
Yes, the entropy depends on the generation process. The study you link to has the answer for the (fixed) process used there:


  To overcome this [flaw in the original program], we generated the full list of eight-character pronounceable passwords without duplicates (≈ 1.2 billion) and assigned each password on this list with equal probability, resulting in 30.2 bits of entropy.


That is equivalent to five base 64 characters. I.e. you lose about 2.25 bits of entropy per character by making the password pronounceable, compared to using random base 64 passwords.

However, like the implementation they used, it is possible the algorithm is flawed and does not generate all possible pronounceable passwords with equal probability. In that case you lose even more entropy. So I would check the program carefully before relying on it.