Cast iron rads:- even heating- doesn't suck moisture out of the air- most people recommend keeping them if you have them as they are superior to baseboard or forced air heat. - doesn't require new ductwork.

You could use a moisture detector to test the area in question.

Given the fact that it has been almost 10 months since the water overflow issue, I can't imagine the bowing of the floor and the spots on the vent cover are from the moisture back then.

It would need to be a flow indicator type - the moisture sensor version would be useless in this application as @JD Martin pointed out. 

I'd just be concerned because it says moisture resistant but not waterproof -- hard to argue against your soaking experiment though. 

Install new Housewrap weather and moisture barrier.

The reason being is that eng'd is more adaptable to fluctuations in moisture content, and does not tend to warp as bad, therefore is in higher demand.  

You don't want to end up with too much moisture in the room that can cause more problems. 

I also like that it provides better moisture control which is good for my investment, it’s very humid here, walls will literally drip. 

I had an inspector go out and take a look at it during construction and he found MAJOR problems ranging from possible asbestos insulation being airborne, lead-based paint cracking, cracks in the foundation and crawl space, old knob and tube wiring, moisture and mold issues, roof shingles replacement, and loads of other issues.Rather than talking about them, I made a playlist of the inspection here: https://www.youtube.com/watch?