I posted a similar question on a home owners forum but I think you
guys may know a lot more about things like this.

My wife can be sort of compulsive about her cleaning. She vacuums the
floor every week (good)...

She got a floor cleaning machine and every 2 - 3 weeks she cleans
these floors with Bona hardwood cleaner and complains constantly about
how much dirt is in the wash water it collects. (well, maybe OK) but
will all this high-powered cleaning damage the polyurethane sealant on
the floor?

Any advice, suggestions, symphathy, better ways to clean floors?

Thanks,
Richard