I just purchased a 1993 F336. The step leading to the cabin was loose. I peeled back the carpet on the vertical wall above
the step & found the wood wet & falling apart.
Is there any concern that this may lead to the structure of
the hull (stringers). It is glassed to the floor, but was it
glassed to the floor after the hull is encapsulated to itself?

umm... if that part is wet and rotten, there might have other part... did you get a survey on the boat BEFORE buying?

Yes. He told me that he did pick up moisture readings in the
area. But because there was some standing water in bilge
area under step.
The wood is only 3/8 thick. I would find it hard to belive that it is tied to the structure of the boat hull.
I thought I read that the stringers in a Formula are encapsulated in resin.

maybe the new one with the grid system. but oldest like yours and mine... I just changed my main stringer in my engine compartement

Hard to say really. You will have to dig into it and hope for the best.

I don't think that is part of the structure, I could be wrong, Formulas had that issue in EVERY SR1 boat...

Well I found the cause. The previous ower unbolted the port side adjustable footrest, as it's inoperable. And never re-secured, leaving mounting holes open.
It was leaking down on top of glass that incases the fuel tank.
There happend to be a small area of open glass that allowed the water in at the top of that bulkhead piece of wood dividing the cabin & cockpit.
I had to cut out 1.5 by 1.5 ft section & replace wood.
It didn't go all the way down to the bottom of the hull.
Even though I still have not got a anwser on weather
the bulkhead is glassed in after hull glass is layed. I still think
that this bulkhead has no structural being to the boat.

Same issue on my 402 sr1. No structural bearing on that piece.