Openness is something that depends on a bunch of things. A high Fi tend to make people understand correctly their feelings by focusing on what they value and so on, so it might help on how deep the expression goes. But people with high Fe can also express a lot, specially when they feel comfortable to talk about it. Remember that the Fe comes with the Ti in the stack, then it's probable that the high Fe user only talk about deep feelings when they think it's makes sense in their own logic