It is normal that hot water systems are set to >60 degrees to ensure no growth of bacteria but it is also a requirement in any new installation that a tempering valve be installed to protect against risk of scalding, at least in bathrooms. IE safety requires both the higher tank temperature and the tempering valve.
On another matter unrelated to plumbing we had legal advice that included the penalties that might be faced by the OC for exposing someone to risk of serious harm. IE nothing bad needed to actually occur. It was enough to be liable if we did not remedy a serious safety risk.
It seems bizarre that the OC has a problem with such a routine matter. I would think the only technical matter to address is whether it would be better to have one tempering valve for the entire system or separate ones at the entry point of each unit or just on the bathroom of each unit. The last option can be useful to have hotter water in the kitchen for washing up.
I think there would usually be a point at which you could shut off the water just for your unit and a point at which the pipes inside the unit become your responsibility. Is is possible to install a tempering valve on a bit of pipe that is your responsibility and feeds the shower?