I have had four Rvs.
A 79 Prowler, 2001 Wilderness, 2010 Sabre, and 2021 Momentum. None of them are foam core construction.
I hav a few friends that had RVs using that construction. They all had problems. They all sold them and got something that did not use foam core construction.
I have read of some that repaired theirs. I have little faith in the durability of those fixes.
I think RVs built that way should be avoided
I read some years back that the industry did a study that found that the average new towable RV owner used it 2-3 times a year for 3 years and never used it again. Some sold them, others just parked them.
That really explains why some are not built to last.