you should ask whoever you heard that from to show you some data.
yes, formestane could be converted into 4-hydroxy-testosterone in the body.
but you would need to use a very lot more than what is needed to illicit an anabolic/androgenic effect to an extent it will supress hpta function.
btw, inhibit it contains atd, another ai that can convert into 1,4,6 testosterone, and 6-bromo can convert into 6-bromo testosterone.
but, like has already been said, much more would be needed, than is required for aromatase inhibitory effects.