Wow, that chassis must be immensely shaking up the house to develop so many issues related to earthquaking. I hope you get proper resolution.
Why would anyone install a tiled surface with grout in a motorhome is beyond my comprehention. This is why laminate flooring is so popular as an upscaled finish flooring choice. Vinyl and carpeting is naturally most popular, and most flexible for earthquaking.
It is for the reasons the OP is experiencing, why I was proactive and replaced my front coil springs
(DETAILS HERE) with softer ones.... to minimize earthquaking, in-part, to be easier on the integrity of the house.