Are you saying that the cypress requires a dormant period to produce adult foliage?

Not necessarily, all plants require dormancy; the initiating
environmental factors vary. Temperature is one factor, there are many.
It could be that more than one is required. The Hemerocallis was only
an example of environmental factors turning genes “on and off”. In
some ways it is akin to animals aging and maturing.

The trees are in full sun. I can manipulate some environmental factors, such as providing additional food in the form of Osmocote.

More nutrients and light are factors that are secondary to most,
especially physical characteristics, gene expression.

They are watered daily & dry out in between.

That is an excellent habit regardless of the age, within reason, and
species!

Cupressus sempervirens (which I have grown before) is unique among the temperate conifers in that it does not require dormancy. After a brief cooling off in the fall, I can grow it under fluorescent lights all winter.

The “cooling off” period and the photoperiodism cause some
physiological changes that influence gene expression. Without a good
bit of literature research I cannot say with absolute certainty how
big of a role, but, I am certain that they play a roll. Again, all
plants “go through” and have dormancy, regardless of the reason.

Which would provide a quicker transition to adult foliage, growing
all winter or a longer dormancy?

Part of the reason you are experiencing a prolonged growth of immature
foliage may be due to the plant(s) not experiencing a prolonged or
protracted dormancy.

As a bonsai, the trees look OK as they are, and they are growing, but they appear flimsy. I would like to get some hefty growth on them.

To tighten the foliage up try pinching the shoots. Pinching
accomplishes much and has varied results. It is important to remember
that, As is learned by all who endeavor in the art of Bonsai, patients
is the secret to everything; although, it is, admittedly, often the
most difficult and most tedious of the things that can be learned from
the art and science of bonsai.