There was a short clip in an old news article on the Titan that showed a large filament would structure being made. I don't know if that was a video of the Titan being made or just a representative clip or even an un-related clip thrown in as filler.
Assuming it was an actual clip of the actual Titan, I think it's a pretty safe bet that someone conflated the mechanics of internal pressure vessels with external pressure vessels as was previously stated here.
It probably would've been stronger and lighter to just take the CF out and just cast the hull out of the epoxy matrix material. (Not really, but in a sense that's all that's providing a significant portion of the force holding up two miles of ocean, it's just glueing a bunch of thin shells together with the entire ocean trying to roll them up).
My senior design project in college involved a high level design of an electric aircraft. It was a comaborative effort between about 20 engineering students (in competition with another 20ish). Iirc in 2012 we chose NOT to go with a composite wing spar (simple (ish) bending loading, vs complex compressive loading) simply because we couldn't find good literature on endurance limits.
I encountered this a lot in the synthetic rope/textiles world too but: all we know about steel comes from many many many hard lessons learned in the 18th, 19th, and 20th centuries. There is no shortcut to relearning those with a new material that's been around since the 80s. There is a long list of hard lessons won in early GF and CF sailboats. I wonder if any of the engineers were aware of those. Something makes me think no.