How about a piece of 5/8 in. plywood glued in each spot. Guess it would depend on what size gap. My dad laid floors for years when I was a kid. He never used anything but what was used as underlayment. Need to be firm as someone step on a Duct tape job & it would probably crack & break. If that other stuff has any spongyness to it same thing would happen.

Tough question. I am familiar with what the North Florida environment can do to most anything made of wood, so you are right to be concerned. Moisture passing through a material that then condenses on a barrier is where there could be a problem. Since the crawlspace is unconditioned, then I would assume that you at least have some means for air exchange or venting and that the ground is covered with a moisture barrier. Very interesting question. Have you consulted with the flooring manufacturer directly about this?

I know , but constructive criticism only please . How would a pro fix this if it is incorrect?

What is the nature of the failure on the plywood you're referring to? I've probably laid hundreds of thousands of square feet of plywood over concrete and can't think of one failure I could attribute to the installation method (i.e. the failures have all been caused by other factors, like a flood). Granted we go a little overboard in that we flat trowel cold bond adhesive on the concrete at 50'/gallon, lay in heavy poly sheeting, trowel another layer of mastic over that at 32'/gallon, lay in the plywood, shoot it down with 1-1/2" hardened coil nails and fasten any loose areas with tapcons. Before sheet vinyl fell out of favor we used it under plywood all the time in conjunction with adhesive. I've had a few jobs recently where the client wanted something better that visqueen so we used a membrane like Traxxshield99 with seam tape. The plywood subfloors I have seen fail due to installation method, are almost always laid dry over a single layer of black felt paper (which is not a suitable moisture barrier), then shot or screwed down. I don't think there's any need to build up a subfloor like that and affect the relationship to doors and steps, but if the advantages were deemed to be beneficial, I'd recommend a moisture barrier, 1x4s fastened to the concrete 12" on center and a layer of 3/4" plywood over that, with the joints laid on the 1x4s. This can be a little complicated because it would be nice to have p.t. lumber for the 1x4s but they're generally soaking wet upon purchase and there may be an issue using steel fasteners.